Composition comprising antibody that binds to domain II of HER2 and acidic variants thereof

ABSTRACT

A composition comprising a main species HER2 antibody that binds to domain II of HER2 and acidic variants thereof is described. Pharmaceutical formulations comprising the composition, and therapeutic uses for the composition are also disclosed.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/024,825, filed 30 Jan. 2008, the disclosure of whichis hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention concerns a composition comprising a main speciesHER2 antibody that binds to domain II of HER2, and acidic variantsthereof. The invention also relates to pharmaceutical formulationscomprising the composition, and therapeutic uses for the composition.

BACKGROUND OF THE INVENTION HER2 Antibodies

The HER family of receptor tyrosine kinases are important mediators ofcell growth, differentiation and survival. The receptor family includesfour distinct members including epidermal growth factor receptor (EGFR,ErbB1, or HER1), HER2 (ErbB2 or p185^(neu)), HER3 (ErbB3) and HER4(ErbB4 or tyro2).

EGFR, encoded by the erbB1 gene, has been causally implicated in humanmalignancy. In particular, increased expression of EGFR has beenobserved in breast, bladder, lung, head, neck and stomach cancer as wellas glioblastomas. Increased EGFR receptor expression is often associatedwith increased production of the EGFR ligand, transforming growth factoralpha (TGF-α), by the same tumor cells resulting in receptor activationby an autocrine stimulatory pathway. Baselga and Mendelsohn Pharmac.Ther. 64:127-154 (1994). Monoclonal antibodies directed against the EGFRor its ligands, TGF-α and EGF, have been evaluated as therapeutic agentsin the treatment of such malignancies. See, e.g., Baselga andMendelsohn., supra; Masui et al. Cancer Research 44:1002-1007 (1984);and Wu et al. J. Clin. Invest. 95:1897-1905 (1995).

The second member of the HER family, p185^(neu), was originallyidentified as the product of the transforming gene from neuroblastomasof chemically treated rats. The activated form of the neu proto-oncogeneresults from a point mutation (valine to glutamic acid) in thetransmembrane region of the encoded protein. Amplification of the humanhomolog of neu is observed in breast and ovarian cancers and correlateswith a poor prognosis (Slamon et al., Science, 235:177-182 (1987);Slamon et al., Science, 244:707-712 (1989); and U.S. Pat. No.4,968,603). To date, no point mutation analogous to that in the neuproto-oncogene has been reported for human tumors. Overexpression ofHER2 (frequently but not uniformly due to gene amplification) has alsobeen observed in other carcinomas including carcinomas of the stomach,endometrium, salivary gland, lung, kidney, colon, thyroid, pancreas andbladder. See, among others, King et al., Science, 229:974 (1985); Yokotaet al., Lancet: 1:765-767 (1986); Fukushige et al., Mol Cell Biol.,6:955-958 (1986); Guerin et al., Oncogene Res., 3:21-31 (1988); Cohen etal., Oncogene, 4:81-88 (1989); Yonemura et al., Cancer Res., 51:1034(1991); Borst et al., Gynecol. Oncol., 38:364 (1990); Weiner et al.,Cancer Res., 50:421-425 (1990); Kern et al., Cancer Res., 50:5184(1990); Park et al., Cancer Res., 49:6605 (1989); Zhau et al., Mol.Carcinog., 3:254-257 (1990); Aasland et al. Br. J. Cancer 57:358-363(1988); Williams et al. Pathobiology 59:46-52 (1991); and McCann et al.,Cancer, 65:88-92 (1990). HER2 may be overexpressed in prostate cancer(Gu et al. Cancer Lett. 99:185-9 (1996); Ross et al. Hum. Pathol.28:827-33 (1997); Ross et al. Cancer 79:2162-70 (1997); and Sadasivan etal. J. Urol. 150:126-31 (1993)).

Antibodies directed against the rat p185^(neu) and human HER2 proteinproducts have been described. Drebin and colleagues have raisedantibodies against the rat neu gene product, p185^(neu) See, forexample, Drebin et al., Cell 41:695-706 (1985); Myers et al., Meth.Enzym. 198:277-290 (1991); and WO94/22478. Drebin et al. Oncogene2:273-277 (1988) report that mixtures of antibodies reactive with twodistinct regions of p185^(neu) result in synergistic anti-tumor effectson neu-transformed NIH-3T3 cells implanted into nude mice. See also U.S.Pat. No. 5,824,311 issued Oct. 20, 1998.

Hudziak et al., Mol. Cell. Biol. 9(3): 1165-1172 (1989) describe thegeneration of a panel of HER2 antibodies which were characterized usingthe human breast tumor cell line SK-BR-3. Relative cell proliferation ofthe SK-BR-3 cells following exposure to the antibodies was determined bycrystal violet staining of the monolayers after 72 hours. Using thisassay, maximum inhibition was obtained with the antibody called 4D5which inhibited cellular proliferation by 56%. Other antibodies in thepanel reduced cellular proliferation to a lesser extent in this assay.The antibody 4D5 was further found to sensitize HER2-overexpressingbreast tumor cell lines to the cytotoxic effects of TNF-α. See also U.S.Pat. No. 5,677,171 issued Oct. 14, 1997. The HER2 antibodies discussedin Hudziak et al. are further characterized in Fendly et al. CancerResearch 50:1550-1558 (1990); Kotts et al. In Vitro 26(3):59A (1990);Sarup et al. Growth Regulation 1:72-82 (1991); Shepard et al. J. Clin.Immunol. 11(3):117-127 (1991); Kumar et al. Mol. Cell. Biol.11(2):979-986 (1991); Lewis et al. Cancer Immunol. Immunother.37:255-263 (1993); Pietras et al. Oncogene 9:1829-1838 (1994); Vitettaet al. Cancer Research 54:5301-5309 (1994); Sliwkowski et al. J. Biol.Chem. 269(20): 14661-14665 (1994); Scott et al. J. Biol. Chem.266:14300-5 (1991); D'souza et al. Proc. Natl. Acad. Sci. 91:7202-7206(1994); Lewis et al. Cancer Research 56:1457-1465 (1996); and Schaeferet al. Oncogene 15:1385-1394 (1997).

A recombinant humanized version of the murine HER2 antibody 4D5(huMAb4D5-8, rhuMAb HER2, Trastuzumab or HERCEPTIN®; U.S. Pat. No.5,821,337) is clinically active in patients with HER2-overexpressingmetastatic breast cancers that have received extensive prior anti-cancertherapy (Baselga et al., J. Clin. Oncol. 14:737-744 (1996)). Trastuzumabreceived marketing approval from the Food and Drug Administration Sep.25, 1998 for the treatment of patients with metastatic breast cancerwhose tumors overexpress the HER2 protein.

Other HER2 antibodies with various properties have been described inTagliabue et al. Int. J. Cancer 47:933-937 (1991); McKenzie et al.Oncogene 4:543-548 (1989); Maier et al. Cancer Res. 51:5361-5369 (1991);Bacus et al. Molecular Carcinogenesis 3:350-362 (1990); Stancovski etal. PNAS (USA) 88:8691-8695 (1991); Bacus et al. Cancer Research52:2580-2589 (1992); Xu et al. Int. J. Cancer 53:401-408 (1993);WO94/00136; Kasprzyk et al. Cancer Research 52:2771-2776 (1992); Hancocket al. Cancer Res. 51:4575-4580 (1991); Shawver et al. Cancer Res.54:1367-1373 (1994); Arteaga et al. Cancer Res. 54:3758-3765 (1994);Harwerth et al. J. Biol. Chem. 267:15160-15167 (1992); U.S. Pat. No.5,783,186; and Klapper et al. Oncogene 14:2099-2109 (1997).

Homology screening has resulted in the identification of two other HERreceptor family members; HER3 (U.S. Pat. Nos. 5,183,884 and 5,480,968 aswell as Kraus et al. PNAS (USA) 86:9193-9197 (1989)) and HER4 (EP PatAppln No 599,274; Plowman et al., Proc. Natl. Acad. Sci. USA,90:1746-1750 (1993); and Plowman et al., Nature, 366:473-475 (1993)).Both of these receptors display increased expression on at least somebreast cancer cell lines.

The HER receptors are generally found in various combinations in cellsand heterodimerization is thought to increase the diversity of cellularresponses to a variety of HER ligands (Earp et al. Breast CancerResearch and Treatment 35: 115-132 (1995)). EGFR is bound by sixdifferent ligands; epidermal growth factor (EGF), transforming growthfactor alpha (TGF-α), amphiregulin, heparin binding epidermal growthfactor (HB-EGF), betacellulin and epiregulin (Groenen et al. GrowthFactors 11:235-257 (1994)). A family of heregulin proteins resultingfrom alternative splicing of a single gene are ligands for HER3 andHER4. The heregulin family includes alpha, beta and gamma heregulins(Holmes et al., Science, 256:1205-1210 (1992); U.S. Pat. No. 5,641,869;and Schaefer et al. Oncogene 15:1385-1394 (1997)); neu differentiationfactors (NDFs), glial growth factors (GGFs); acetylcholine receptorinducing activity (ARIA); and sensory and motor neuron derived factor(SMDF). For a review, see Groenen et al. Growth Factors 11:235-257(1994); Lemke, G. Molec. & Cell. Neurosci. 7:247-262 (1996) and Lee etal. Pharm. Rev. 47:51-85 (1995). Recently three additional HER ligandswere identified; neuregulin-2 (NRG-2) which is reported to bind eitherHER3 or HER4 (Chang et al. Nature 387 509-512 (1997); and Carraway et alNature 387:512-516 (1997)); neuregulin-3 which binds HER4 (Zhang et al.PNAS (USA) 94(18):9562-7 (1997)); and neuregulin-4 which binds HER4(Harari et al. Oncogene 18:2681-89 (1999)) HB-EGF, betacellulin andepiregulin also bind to HER4.

While EGF and TGFα do not bind HER2, EGF stimulates EGFR and HER2 toform a heterodimer, which activates EGFR and results intransphosphorylation of HER2 in the heterodimer. Dimerization and/ortransphosphorylation appears to activate the HER2 tyrosine kinase. SeeEarp et al., supra. Likewise, when HER3 is co-expressed with HER2, anactive signaling complex is formed and antibodies directed against HER2are capable of disrupting this complex (Sliwkowski et al., J. Biol.Chem., 269(20): 14661-14665 (1994)). Additionally, the affinity of HER3for heregulin (HRG) is increased to a higher affinity state whenco-expressed with HER2. See also, Levi et al., Journal of Neuroscience15: 1329-1340 (1995); Morrissey et al., Proc. Natl. Acad. Sci. USA 92:1431-1435 (1995); and Lewis et al., Cancer Res., 56:1457-1465 (1996)with respect to the HER2-HER3 protein complex. HER4, like HER3, forms anactive signaling complex with HER2 (Carraway and Cantley, Cell 78:5-8(1994)).

To target the HER signaling pathway, rhuMAb 2C4 (Pertuzumab) wasdeveloped as a humanized antibody that inhibits the dimerization of HER2with other HER receptors, thereby inhibiting ligand-drivenphosphorylation and activation, and downstream activation of the RAS andAKT pathways. In a phase I trial of Pertuzumab as a single agent fortreating solid tumors, 3 subjects with advanced ovarian cancer weretreated with pertuzumab. One had a durable partial response, and anadditional subject had stable disease for 15 weeks. Agus et al. Proc AmSoc Clin Oncol 22: 192, Abstract 771 (2003).

Antibody Variant Compositions

U.S. Pat. No. 6,339,142 describes a HER2 antibody composition comprisinga mixture of anti-HER2 antibody and one or more acidic variants thereof,wherein the amount of the acidic variant(s) is less than about 25%.Trastuzumab is the exemplified HER2 antibody.

Reid et al. Poster presented at Well Characterized BiotechPharmaceuticals conference (January, 2003) “Effects of Cell CultureProcess Changes on Humanized Antibody Characteristics” describes anunnamed, humanized IgG1 antibody composition with N-terminalheterogeneities due to combinations of VHS signal peptide, N-terminalglutamine, and pyroglutamic acid on the heavy chain thereof.

Harris et al. “The Ideal Chromatographic Antibody CharacterizationMethod” talk presented at the IBC Antibody Production Conference(February, 2002) reports a VHS extension on the heavy chain of E25, ahumanized anti-IgE antibody.

Rouse et al. Poster presented at WCBP “‘Top Down’ GlycoproteinCharacterization by High Resolution Mass Spectrometry and ItsApplication to Biopharmaceutical Development” (Jan. 6-9, 2004) describesa monoclonal antibody composition with N-terminal heterogeneityresulting from ⁻³AHS or ⁻²HS signal peptide residues on the light chainthereof.

In a presentation at IBC Meeting (September, 2000) “Strategic Use ofComparability Studies and Assays for Well Characterized Biologicals,”Jill Porter discussed a late-eluting form of ZENAPAX™ with three extraamino acid residues on the heavy chain thereof.

US2006/0018899 describes a composition comprising a main speciespertuzumab antibody and an amino-terminal leader extension variant, aswell as other variant forms of the pertuzumab antibody.

SUMMARY OF THE INVENTION

According to a first aspect, the invention concerns a compositioncomprising a main species HER2 antibody that binds to domain II of HER2,and acidic variants thereof wherein the acidic variants include glycatedvariant, disulfide reduced variant, or non-reducible variant.Preferably, the acidic variants include glycated variant, deamidatedvariant, disulfide reduced variant, sialylated variant, andnon-reducible variant. Desirably, the amount of the acidic variants isless than about 25%.

In another aspect, the invention provides a composition comprising amain species HER2 antibody comprising variable light and variable heavysequences in SEQ ID Nos. 3 and 4, respectively, and acidic variants ofthe main species antibody, wherein the acidic variants include glycatedvariant, deamidated variant, disulfide reduced variant, sialylatedvariant, and non-reducible variant.

The invention also concerns pharmaceutical formulations comprising thecompositions in a pharmaceutically acceptable carrier.

Additionally, the invention relates to a method of treating HER2positive cancer in a patient comprising administering the pharmaceuticalformulation to the patient in an amount effective to treat the cancer.With respect to such methods, as demonstrated in the Example herein,preferably the main species antibody and acidic variants haveessentially the same pharmacokinetics.

In another aspect, the invention concerns a method of making apharmaceutical composition comprising: (1) preparing a compositioncomprising a main species HER2 antibody that binds to domain II of HER2,and acidic variants thereof including glycated variant, disulfidereduced variant, or non-reducible variant, and (2) evaluating the acidicvariants in the composition, and confirming that the amount thereof isless than about 25%.

In one embodiment, the acidic variants are evaluated by a methodselected from the group consisting of ion exchange chromatographywherein the composition is treated with sialidase, reduced capilliaryelectrophoresis with sodium dodecyl sulfate (CE-SDS), non-reducedCE-SDS, boronate chromatography, and peptide mapping.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic of the HER2 protein structure, and aminoacid sequences for Domains I-IV (SEQ ID Nos. 19-22, respectively) of theextracellular domain thereof.

FIGS. 2A and 2B depict alignments of the amino acid sequences of thevariable light (V_(L)) (FIG. 2A) and variable heavy (V_(H)) (FIG. 2B)domains of murine monoclonal antibody 2C4 (SEQ ID Nos. 1 and 2,respectively); V_(L) and V_(H) domains of humanized 2C4 version 574 (SEQID Nos. 3 and 4, respectively), and human V_(L) and V_(H) consensusframeworks (hum κ1, light kappa subgroup I; humIII, heavy subgroup III)(SEQ ID Nos. 5 and 6, respectively). Asterisks identify differencesbetween humanized 2C4 version 574 and murine monoclonal antibody 2C4 orbetween humanized 2C4 version 574 and the human framework.Complementarity Determining Regions (CDRs) are in brackets.

FIGS. 3A and 3B show the amino acid sequences of Pertuzumab light chain(SEQ ID No. 15) and heavy chain (SEQ ID No. 16). CDRs are shown in bold.The carbohydrate moiety is attached to Asn 299 of the heavy chain.

FIGS. 4A and 4B show the amino acid sequences of Pertuzumab light chain(SEQ ID No. 17) and heavy chain (SEQ ID No. 18), each including anintact amino terminal signal peptide sequence.

FIG. 5 depicts, schematically, binding of 2C4 at the heterodimericbinding site of HER2, thereby preventing heterodimerization withactivated EGFR or HER3.

FIG. 6 depicts coupling of HER2/HER3 to the MAPK and Akt pathways.

FIG. 7 compares activities of Trastuzumab and Pertuzumab.

FIGS. 8A and 8B show the amino acid sequences of Trastuzumab light chain(SEQ ID No. 13) and heavy chain (SEQ ID No. 14).

FIGS. 9A and 9B depict a variant Pertuzumab light chain sequence (SEQ IDNo. 23) and a variant Pertuzumab heavy chain sequence (SEQ ID No. 24).

FIG. 10 shows experimental design for isolation of cation exchange MP(Main Peak) and AV (Acidic Variants), cell culture, recovery, and PK(pharmacokinetics) evaluation and analytical testing. Freshmedia=standard media; spent media=standard media after 12 days of cellculture, cells were removed by centrifugation. Dissolved oxygen, pH, andother parameters were not controlled.

FIG. 11 shows a typical DIONEX PROPAC™ cation exchange (CEX)chromatogram from Example 1.

FIG. 12 shows analysis of pertuzumab starting material and CEXfractions. AV=acidic variant; MP=main peak; and BV=basic variant.

FIG. 13 reveals CEX of main peak (MP) spiked into cell culture media andincubated for 12 days.

FIG. 14 describes main peak incubation conditions.

FIG. 15 summarizes methods for characterization of acidic variants.

FIG. 16 shows pertuzumab concentration versus time in the PK studies inExample 1.

FIG. 17 provides the area under the curve (AUC) and geometric meanratios from the PK study in Example 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Definitions

The term “main species antibody” herein refers to the antibody aminoacid sequence structure in a composition which is the quantitativelypredominant antibody molecule in the composition. Preferably, the mainspecies antibody is a HER2 antibody, such as an antibody that binds toDomain II of HER2, antibody that inhibits HER dimerization moreeffectively than Trastuzumab, and/or an antibody which binds to aheterodimeric binding site of HER2. The preferred embodiment herein ofthe main species antibody is one comprising the variable light andvariable heavy amino acid sequences in SEQ ID Nos. 3 and 4, and mostpreferably comprising the light chain and heavy chain amino acidsequences in SEQ ID Nos. 15 and 16 (Pertuzumab).

An “amino acid sequence variant” antibody herein is an antibody with anamino acid sequence which differs from a main species antibody.Ordinarily, amino acid sequence variants will possess at least about 70%homology with the main species antibody, and preferably, they will be atleast about 80%, and more preferably at least about 90% homologous withthe main species antibody. The amino acid sequence variants possesssubstitutions, deletions, and/or additions at certain positions withinor adjacent to the amino acid sequence of the main species antibody.Examples of amino acid sequence variants herein include an acidicvariant (e.g. a deamidated antibody variant), a basic variant, theantibody with an amino-terminal leader extension (e.g. VHS-) on one ortwo light chains thereof, antibody with a C-terminal lysine residue onone or two heavy chains thereof, antibody with one or more oxidizedmethionine residues, etc. and includes combinations of variations to theamino acid sequences of heavy and/or light chains.

An “acidic variant” is a variant of the main species antibody which ismore acidic than the main species antibody. An acidic variant has gainednegative charge or lost positive charge relative to the main speciesantibody. Such acidic variants can be resolved using a separationmethodology, such as ion exchange chromatography, that separatesproteins according to charge. Acidic variants of a main species antibodyelute earlier than the main peak upon separation by cation exchangechromatography.

A “disulfide reduced variant” has one more disulfide-bonded cysteine(s)chemically reduced to the free thiol form. This variant can be monitoredby hydrophobic interaction chromatography or by sizing methodology suchas Capillary Electrophoresis with Sodium Dodecyl Sulfate (CE-SDS), e.g.as described in Example 1. Herein, a “non-reducible variant” is avariant of the main species antibody that cannot be chemically reducedto heavy and light chain by treatment with a reducing agent such asdithiothreitol. Such variants can be assessed by treating thecomposition with a reducing agent and evaluating the resultingcomposition using a methodology that evaluates protein size, such asCapillary Electrophoresis with Sodium Dodecyl Sulfate (CE-SDS), forinstance using the techniques described in Example 1 below.

A “glycosylation variant” antibody herein is an antibody with one ormore carbohydrate moeities attached thereto which differ from one ormore carbohydate moieties attached to a main species antibody. Examplesof glycosylation variants herein include antibody with a G1 or G2oligosaccharide structure, instead a G0 oligosaccharide structure,attached to an Fc region thereof, antibody with one or two carbohydratemoieties attached to one or two light chains thereof, antibody with nocarbohydrate attached to one or two heavy chains of the antibody,antibody which is syalidated, etc, as well as combinations of suchglycosylation alterations.

Where the antibody has an Fc region, an oligosaccharide structure suchas that shown in FIG. 14 herein may be attached to one or two heavychains of the antibody, e.g. at residue 299. For Pertuzumab, G0 was thepredominant oligosaccharide structure, with other oligosaccharidestructures such as G0-F, G-1, Man5, Man6, G1-1, G1(1-6), G1(1-3) and G2being found in lesser amounts in the Pertuzumab composition.

Unless indicated otherwise, a “G1 oligosaccharide structure” hereinincludes G1(1-6) and G1(1-3) structures.

For the purposes herein, “sialylated variant” is a variant of the mainspecies antibody comprising one or more sialylated carbohydrate moietiesattached to one or two heavy chains thereof. A sialylated variant can beidentified by evaluating a composition (for example by ion exchangechromatography) with or without sialidase treatment, e.g. as describedin the example.

A “glycated variant” is an antibody to which a sugar, such as glucose,has been covalently attached. This addition can occur by reaction ofglucose with a lysine residue on the protein (e.g. in cell culturemedia). A glycated variant can be identified by mass spectrometryanalysis of the reduced antibody evaluating the increase in mass ofheavy or light chains. A glycated variant can also be quantified byboronate chromatography as explained in Example 1 below. A glycatedvariant differs from a glycosylation variant.

A “deamidated” antibody is one in which one or more asparagine residuesthereof has been derivitized, e.g. to an aspartic acid, a succinimide,or an iso-aspartic acid. An example of a deamidated antibody is apertuzumab variant, wherein Asn-386 and/or Asn-391 on one or two heavychains of pertuzumab are deamidated.

A “amino-terminal leader extension variant” herein refers to a mainspecies antibody with one or more amino acid residues of theamino-terminal leader sequence at the amino-terminus of any one or moreheavy or light chains of the main species antibody. An exemplaryamino-terminal leader extension comprises or consists of three aminoacid residues, VHS, present on one or both light chains of an antibodyvariant.

“Homology” is defined as the percentage of residues in the amino acidsequence variant that are identical after aligning the sequences andintroducing gaps, if necessary, to achieve the maximum percent homology.Methods and computer programs for the alignment are well known in theart. One such computer program is “Align 2”, authored by Genentech,Inc., which was filed with user documentation in the United StatesCopyright Office, Washington, D.C. 20559, on Dec. 10, 1991.

For the purposes herein, “cation exchange analysis” refers to any methodby which a composition comprising two or more compounds is separatedbased on charge differences using a cation exchanger. A cation exchangergenerally comprises covalently bound, negatively charged groups.Preferably, the cation exchanger herein is a weak cation-exchangerand/or comprises a carboxylate functional group, such as the PROPACWCX-10™ cation exchange column sold by Dionex.

A “HER receptor” is a receptor protein tyrosine kinase which belongs tothe HER receptor family and includes EGFR, HER2, HER3 and HER4 receptorsand other members of this family to be identified in the future. The HERreceptor will generally comprise an extracellular domain, which may bindan HER ligand; a lipophilic transmembrane domain; a conservedintracellular tyrosine kinase domain; and a carboxyl-terminal signalingdomain harboring several tyrosine residues which can be phosphorylated.Preferably the HER receptor is native sequence human HER receptor.

The extracellular domain of HER2 comprises four domains, Domain I (aminoacid residues from about 1-195), Domain II (amino acid residues fromabout 196-319), Domain III (amino acid residues from about 320-488), andDomain IV (amino acid residues from about 489-630) (residue numberingwithout signal peptide). See Garrett et al. Mol. Cell. 11: 495-505(2003), Cho et al. Nature 421: 756-760 (2003), Franklin et al. CancerCell 5:317-328 (2004), or Plowman et al. Proc. Natl. Acad. Sci.90:1746-1750 (1993). See, also, FIG. 1 herein.

The terms “ErbB1,” “HER1”, “epidermal growth factor receptor” and “EGFR”are used interchangeably herein and refer to EGFR as disclosed, forexample, in Carpenter et al. Ann. Rev. Biochem. 56:881-914 (1987),including naturally occurring mutant forms thereof (e.g. a deletionmutant EGFR as in Humphrey et al. PNAS (USA) 87:4207-4211 (1990)). erbB1 refers to the gene encoding the EGFR protein product.

The expressions “ErbB2” and “HER2” are used interchangeably herein andrefer to human HER2 protein described, for example, in Semba et al.,PNAS (USA) 82:6497-6501 (1985) and Yamamoto et al. Nature 319:230-234(1986) (Genebank accession number X03363). The term “erbB2” refers tothe gene encoding human ErbB2 and “neu” refers to the gene encoding ratp185^(neu). Preferred HER2 is native sequence human HER2.

“ErbB3” and “HER3” refer to the receptor polypeptide as disclosed, forexample, in U.S. Pat. Nos. 5,183,884 and 5,480,968 as well as Kraus etal. PNAS (USA) 86:9193-9197 (1989).

The terms “ErbB4” and “HER4” herein refer to the receptor polypeptide asdisclosed, for example, in EP Pat Appln No 599,274; Plowman et al.,Proc. Natl. Acad. Sci. USA, 90:1746-1750 (1993); and Plowman et al.,Nature, 366:473-475 (1993), including isoforms thereof, e.g., asdisclosed in WO99/19488, published Apr. 22, 1999.

By “HER ligand” is meant a polypeptide which binds to and/or activatesan HER receptor. The HER ligand of particular interest herein is anative sequence human HER ligand such as epidermal growth factor (EGF)(Savage et al., J. Biol. Chem. 247:7612-7621 (1972)); transforminggrowth factor alpha (TGF-α) (Marquardt et al., Science 223:1079-1082(1984)); amphiregulin also known as schwanoma or keratinocyte autocrinegrowth factor (Shoyab et al. Science 243:1074-1076 (1989); Kimura et al.Nature 348:257-260 (1990); and Cook et al. Mol. Cell. Biol. 11:2547-2557(1991)); betacellulin (Shing et al., Science 259:1604-1607 (1993); andSasada et al. Biochem. Biophys. Res. Commun. 190:1173 (1993));heparin-binding epidermal growth factor (HB-EGF) (Higashiyama et al.,Science 251:936-939 (1991)); epiregulin (Toyoda et al., J. Biol. Chem.270:7495-7500 (1995); and Komurasaki et al. Oncogene 15:2841-2848(1997)); a heregulin (see below); neuregulin-2 (NRG-2) (Carraway et al.,Nature 387:512-516 (1997)); neuregulin-3 (NRG-3) (Zhang et al., Proc.Natl. Acad. Sci. 94:9562-9567 (1997)); neuregulin-4 (NRG-4) (Harari etal. Oncogene 18:2681-89 (1999)) or cripto (CR-1) (Kannan et al. J. Biol.Chem. 272(6):3330-3335 (1997)). HER ligands which bind EGFR include EGF,TGF-α, amphiregulin, betacellulin, HB-EGF and epiregulin. HER ligandswhich bind HER3 include heregulins. HER ligands capable of binding HER4include betacellulin, epiregulin, HB-EGF, NRG-2, NRG-3, NRG-4 andheregulins.

“Heregulin” (HRG) when used herein refers to a polypeptide encoded bythe heregulin gene product as disclosed in U.S. Pat. No. 5,641,869 orMarchionni et al., Nature, 362:312-318 (1993). Examples of heregulinsinclude heregulin-α, heregulin-β1, heregulin-β2 and heregulin-β3 (Holmeset al., Science, 256:1205-1210 (1992); and U.S. Pat. No. 5,641,869); neudifferentiation factor (NDF) (Peles et al. Cell 69: 205-216 (1992));acetylcholine receptor-inducing activity (ARIA) (Falls et al. Cell72:801-815 (1993)); glial growth factors (GGFs) (Marchionni et al.,Nature, 362:312-318 (1993)); sensory and motor neuron derived factor(SMDF) (Ho et al. J. Biol. Chem. 270:14523-14532 (1995)); γ-heregulin(Schaefer et al. Oncogene 15:1385-1394 (1997)). The term includesbiologically active fragments and/or amino acid sequence variants of anative sequence HRG polypeptide, such as an EGF-like domain fragmentthereof (e.g. HRGβ1 ₁₇₇₋₂₄₄).

A “HER dimer” herein is a noncovalently associated dimer comprising atleast two different HER receptors. Such complexes may form when a cellexpressing two or more HER receptors is exposed to an HER ligand and canbe isolated by immunoprecipitation and analyzed by SDS-PAGE as describedin Sliwkowski et al., J. Biol. Chem., 269(20): 14661-14665 (1994), forexample. Examples of such HER dimers include EGFR-HER2, HER2-HER3 andHER3-HER4 heterodimers. Moreover, the HER dimer may comprise two or moreHER2 receptors combined with a different HER receptor, such as HER3,HER4 or EGFR. Other proteins, such as a cytokine receptor subunit (e.g.gp130) may be associated with the dimer.

A “heterodimeric binding site” on HER2, refers to a region in theextracellular domain of HER2 that contacts, or interfaces with, a regionin the extracellular domain of EGFR, HER3 or HER4 upon formation of adimer therewith. The region is found in Domain II of HER2. Franklin etal. Cancer Cell 5:317-328 (2004).

“HER activation” or “HER2 activation” refers to activation, orphosphorylation, of any one or more HER receptors, or HER2 receptors.Generally, HER activation results in signal transduction (e.g. thatcaused by an intracellular kinase domain of a HER receptorphosphorylating tyrosine residues in the HER receptor or a substratepolypeptide). HER activation may be mediated by HER ligand binding to aHER dimer comprising the HER receptor of interest. HER ligand binding toa HER dimer may activate a kinase domain of one or more of the HERreceptors in the dimer and thereby results in phosphorylation oftyrosine residues in one or more of the HER receptors and/orphosphorylation of tyrosine residues in additional substratepolypeptides(s), such as Akt or MAPK intracellular kinases.

The term “antibody” herein is used in the broadest sense andspecifically covers intact monoclonal antibodies, polyclonal antibodies,multispecific antibodies (e.g. bispecific antibodies) formed from atleast two intact antibodies, and antibody fragments, so long as theyexhibit the desired biological activity.

The term “monoclonal antibody” as used herein refers to an antibodyobtained from a population of substantially homogeneous antibodies,i.e., the individual antibodies comprising the population are identicaland/or bind the same epitope, except for possible variants that mayarise during production of the monoclonal antibody, such as thosevariants described herein. In contrast to polyclonal antibodypreparations that typically include different antibodies directedagainst different determinants (epitopes), each monoclonal antibody isdirected against a single determinant on the antigen. In addition totheir specificity, the monoclonal antibodies are advantageous in thatthey are uncontaminated by other immunoglobulins. The modifier“monoclonal” indicates the character of the antibody as being obtainedfrom a substantially homogeneous population of antibodies, and is not tobe construed as requiring production of the antibody by any particularmethod. For example, the monoclonal antibodies to be used in accordancewith the present invention may be made by the hybridoma method firstdescribed by Kohler et al., Nature, 256:495 (1975), or may be made byrecombinant DNA methods (see, e.g., U.S. Pat. No. 4,816,567). The“monoclonal antibodies” may also be isolated from phage antibodylibraries using the techniques described in Clackson et al., Nature,352:624-628 (1991) and Marks et al., J. Mol. Biol., 222:581-597 (1991),for example.

The monoclonal antibodies herein specifically include “chimeric”antibodies in which a portion of the heavy and/or light chain isidentical with or homologous to corresponding sequences in antibodiesderived from a particular species or belonging to a particular antibodyclass or subclass, while the remainder of the chain(s) is identical withor homologous to corresponding sequences in antibodies derived fromanother species or belonging to another antibody class or subclass, aswell as fragments of such antibodies, so long as they exhibit thedesired biological activity (U.S. Pat. No. 4,816,567; and Morrison etal., Proc. Natl. Acad. Sci. USA, 81:6851-6855 (1984)). Chimericantibodies of interest herein include “primatized” antibodies comprisingvariable domain antigen-binding sequences derived from a non-humanprimate (e.g. Old World Monkey, Ape etc) and human constant regionsequences.

“Antibody fragments” comprise a portion of an intact antibody,preferably comprising the antigen-binding or variable region thereof.Examples of antibody fragments include Fab, Fab′, F(ab′)₂, and Fvfragments; diabodies; linear antibodies; single-chain antibodymolecules; and multispecific antibodies formed from antibodyfragment(s).

An “intact antibody” is one which comprises an antigen-binding variableregion as well as a light chain constant domain (CL) and heavy chainconstant domains, C_(H)1, C_(H)2 and C_(H)3. The constant domains may benative sequence constant domains (e.g. human native sequence constantdomains) or amino acid sequence variants thereof. Preferably, the intactantibody has one or more effector functions, and comprises anoligosaccharide structure attached to one or two heavy chains thereof.

Antibody “effector functions” refer to those biological activitiesattributable to the Fc region (a native sequence Fc region or amino acidsequence variant Fc region) of an antibody. Examples of antibodyeffector functions include C1q binding; complement dependentcytotoxicity; Fc receptor binding; antibody-dependent cell-mediatedcytotoxicity (ADCC); phagocytosis; down regulation of cell surfacereceptors (e.g. B cell receptor; BCR), etc.

The term “Fc region” herein is used to define a C-terminal region of animmunoglobulin heavy chain, including native-sequence Fc regions andvariant Fc regions. Although the boundaries of the Fc region of animmunoglobulin heavy chain might vary, the human IgG heavy-chain Fcregion is usually defined to stretch from an amino acid residue atposition Cys226, or from Pro230, to the carboxyl-terminus thereof. TheC-terminal lysine (residue 447 according to the EU numbering system) ofthe Fc region may be removed, for example, during production orpurification of the antibody, or by recombinantly engineering thenucleic acid encoding a heavy chain of the antibody. Accordingly, acomposition of intact antibodies may comprise antibody populations withall K447 residues removed, antibody populations with no K447 residuesremoved, and antibody populations having a mixture of antibodies withand without the K447 residue.

Unless indicated otherwise herein, the numbering of the residues in animmunoglobulin heavy chain is that of the EU index as in Kabat et al.,Sequences of Proteins of Immunological Interest, 5th Ed. Public HealthService, National Institutes of Health, Bethesda, Md. (1991). The “EUindex as in Kabat” refers to the residue numbering of the human IgG1 EUantibody.

Depending on the amino acid sequence of the constant domain of theirheavy chains, intact antibodies can be assigned to different “classes”.There are five major classes of intact antibodies: IgA, IgD, IgE, IgG,and IgM, and several of these may be further divided into “subclasses”(isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgA, and IgA2. The heavy-chainconstant domains that correspond to the different classes of antibodiesare called α, δ, ε, γ, and μ, respectively. The subunit structures andthree-dimensional configurations of different classes of immunoglobulinsare well known.

“Antibody-dependent cell-mediated cytotoxicity” and “ADCC” refer to acell-mediated reaction in which nonspecific cytotoxic cells that expressFc receptors (FcRs) (e.g. Natural Killer (NK) cells, neutrophils, andmacrophages) recognize bound antibody on a target cell and subsequentlycause lysis of the target cell. The primary cells for mediating ADCC, NKcells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII andFcγRIII. FcR expression on hematopoietic cells in summarized is Table 3on page 464 of Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991). Toassess ADCC activity of a molecule of interest, an in vitro ADCC assay,such as that described in U.S. Pat. No. 5,500,362 or 5,821,337 may beperformed. Useful effector cells for such assays include peripheralblood mononuclear cells (PBMC) and Natural Killer (NK) cells.Alternatively, or additionally, ADCC activity of the molecule ofinterest may be assessed in vivo, e.g., in a animal model such as thatdisclosed in Clynes et al. PNAS (USA) 95:652-656 (1998).

“Human effector cells” are leukocytes which express one or more FcRs andperform effector functions. Preferably, the cells express at leastFcγRIII and perform ADCC effector function. Examples of human leukocyteswhich mediate ADCC include peripheral blood mononuclear cells (PBMC),natural killer (NK) cells, monocytes, cytotoxic T cells and neutrophils;with PBMCs and NK cells being preferred. The effector cells may beisolated from a native source thereof, e.g. from blood or PBMCs asdescribed herein.

The terms “Fc receptor” or “FcR” are used to describe a receptor thatbinds to the Fc region of an antibody. The preferred FcR is a nativesequence human FcR. Moreover, a preferred FcR is one which binds an IgGantibody (a gamma receptor) and includes receptors of the FcγRI, FcγRII,and Fcγ RIII subclasses, including allelic variants and alternativelyspliced forms of these receptors. FcγRII receptors include FcγRIIA (an“activating receptor”) and FcγRIIB (an “inhibiting receptor”), whichhave similar amino acid sequences that differ primarily in thecytoplasmic domains thereof. Activating receptor FcγRIIA contains animmunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmicdomain. Inhibiting receptor FcγRIIB contains an immunoreceptortyrosine-based inhibition motif (ITIM) in its cytoplasmic domain. (seereview M. in Daëron, Annu. Rev. Immunol. 15:203-234 (1997)). FcRs arereviewed in Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991); Capelet al., Immunomethods 4:25-34 (1994); and de Haas et al., J. Lab. Clin.Med. 126:330-41 (1995). Other FcRs, including those to be identified inthe future, are encompassed by the term “FcR” herein. The term alsoincludes the neonatal receptor, FcRn, which is responsible for thetransfer of maternal IgGs to the fetus (Guyer et al., J. Immunol.117:587 (1976) and Kim et al., J. Immunol. 24:249 (1994)).

“Complement dependent cytotoxicity” or “CDC” refers to the ability of amolecule to lyse a target in the presence of complement. The complementactivation pathway is initiated by the binding of the first component ofthe complement system (C1q) to a molecule (e.g. an antibody) complexedwith a cognate antigen. To assess complement activation, a CDC assay,e.g. as described in Gazzano-Santoro et al., J. Immunol. Methods 202:163(1996), may be performed.

“Native antibodies” are usually heterotetrameric glycoproteins of about150,000 daltons, composed of two identical light (L) chains and twoidentical heavy (H) chains. Each light chain is linked to a heavy chainby one covalent disulfide bond, while the number of disulfide linkagesvaries among the heavy chains of different immunoglobulin isotypes. Eachheavy and light chain also has regularly spaced intrachain disulfidebridges. Each heavy chain has at one end a variable domain (V_(H))followed by a number of constant domains. Each light chain has avariable domain at one end (V_(L)) and a constant domain at its otherend. The constant domain of the light chain is aligned with the firstconstant domain of the heavy chain, and the light-chain variable domainis aligned with the variable domain of the heavy chain. Particular aminoacid residues are believed to form an interface between the light chainand heavy chain variable domains.

The term “variable” refers to the fact that certain portions of thevariable domains differ extensively in sequence among antibodies and areused in the binding and specificity of each particular antibody for itsparticular antigen. However, the variability is not evenly distributedthroughout the variable domains of antibodies. It is concentrated inthree segments called hypervariable regions both in the light chain andthe heavy chain variable domains. The more highly conserved portions ofvariable domains are called the framework regions (FRs). The variabledomains of native heavy and light chains each comprise four FRs, largelyadopting a β-sheet configuration, connected by three hypervariableregions, which form loops connecting, and in some cases forming part of,the β-sheet structure. The hypervariable regions in each chain are heldtogether in close proximity by the FRs and, with the hypervariableregions from the other chain, contribute to the formation of theantigen-binding site of antibodies (see Kabat et al., Sequences ofProteins of Immunological Interest, 5th Ed. Public Health Service,National Institutes of Health, Bethesda, Md. (1991)). The constantdomains are not involved directly in binding an antibody to an antigen,but exhibit various effector functions, such as participation of theantibody in antibody dependent cellular cytotoxicity (ADCC).

The term “hypervariable region” when used herein refers to the aminoacid residues of an antibody which are responsible for antigen-binding.The hypervariable region generally comprises amino acid residues from a“complementarity determining region” or “CDR” (e.g. residues 24-34 (L1),50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35(H1), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain;Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed.Public Health Service, National Institutes of Health, Bethesda, Md.(1991)) and/or those residues from a “hypervariable loop” (e.g. residues26-32 (L1), 50-52 (L2) and 91-96 (L3) in the light chain variable domainand 26-32 (H1), 53-55 (H2) and 96-101 (H3) in the heavy chain variabledomain; Chothia and Lesk J. Mol. Biol. 196:901-917 (1987)). “FrameworkRegion” or “FR” residues are those variable domain residues other thanthe hypervariable region residues as herein defined.

Papain digestion of antibodies produces two identical antigen-bindingfragments, called “Fab” fragments, each with a single antigen-bindingsite, and a residual “Fc” fragment, whose name reflects its ability tocrystallize readily. Pepsin treatment yields an F(ab′)₂ fragment thathas two antigen-binding sites and is still capable of cross-linkingantigen.

“Fv” is the minimum antibody fragment which contains a completeantigen-recognition and antigen-binding site. This region consists of adimer of one heavy chain and one light chain variable domain in tight,non-covalent association. It is in this configuration that the threehypervariable regions of each variable domain interact to define anantigen-binding site on the surface of the V_(H)-V_(L) dimer.Collectively, the six hypervariable regions confer antigen-bindingspecificity to the antibody. However, even a single variable domain (orhalf of an Fv comprising only three hypervariable regions specific foran antigen) has the ability to recognize and bind antigen, although at alower affinity than the entire binding site.

The Fab fragment also contains the constant domain of the light chainand the first constant domain (CH1) of the heavy chain. Fab′ fragmentsdiffer from Fab fragments by the addition of a few residues at thecarboxy terminus of the heavy chain CH1 domain including one or morecysteines from the antibody hinge region. Fab′-SH is the designationherein for Fab′ in which the cysteine residue(s) of the constant domainsbear at least one free thiol group. F(ab′)₂ antibody fragmentsoriginally were produced as pairs of Fab′ fragments which have hingecysteines between them. Other chemical couplings of antibody fragmentsare also known.

The “light chains” of antibodies from any vertebrate species can beassigned to one of two clearly distinct types, called kappa (κ) andlambda (λ), based on the amino acid sequences of their constant domains.

“Single-chain Fv” or “scFv” antibody fragments comprise the V_(H) andV_(L) domains of antibody, wherein these domains are present in a singlepolypeptide chain. Preferably, the Fv polypeptide further comprises apolypeptide linker between the V_(H) and V_(L) domains which enables thescFv to form the desired structure for antigen binding. For a review ofscFv see Plückthun in The Pharmacology of Monoclonal Antibodies, vol.113, Rosenburg and Moore eds., Springer-Verlag, New York, pp. 269-315(1994). HER2 antibody scFv fragments are described in WO93/16185; U.S.Pat. No. 5,571,894; and U.S. Pat. No. 5,587,458.

The term “diabodies” refers to small antibody fragments with twoantigen-binding sites, which fragments comprise a variable heavy domain(V_(H)) connected to a variable light domain (V_(L)) in the samepolypeptide chain (V_(H)-V_(L)). By using a linker that is too short toallow pairing between the two domains on the same chain, the domains areforced to pair with the complementary domains of another chain andcreate two antigen-binding sites. Diabodies are described more fully in,for example, EP 404,097; WO 93/11161; and Hollinger et al., Proc. Natl.Acad. Sci. USA, 90:6444-6448 (1993).

“Humanized” forms of non-human (e.g., rodent) antibodies are chimericantibodies that contain minimal sequence derived from non-humanimmunoglobulin. For the most part, humanized antibodies are humanimmunoglobulins (recipient antibody) in which residues from ahypervariable region of the recipient are replaced by residues from ahypervariable region of a non-human species (donor antibody) such asmouse, rat, rabbit or nonhuman primate having the desired specificity,affinity, and capacity. In some instances, framework region (FR)residues of the human immunoglobulin are replaced by correspondingnon-human residues. Furthermore, humanized antibodies may compriseresidues that are not found in the recipient antibody or in the donorantibody. These modifications are made to further refine antibodyperformance. In general, the humanized antibody will comprisesubstantially all of at least one, and typically two, variable domains,in which all or substantially all of the hypervariable loops correspondto those of a non-human immunoglobulin and all or substantially all ofthe FRs are those of a human immunoglobulin sequence. The humanizedantibody optionally also will comprise at least a portion of animmunoglobulin constant region (Fc), typically that of a humanimmunoglobulin. For further details, see Jones et al., Nature321:522-525 (1986); Riechmann et al., Nature 332:323-329 (1988); andPresta, Curr. Op. Struct. Biol. 2:593-596 (1992).

Humanized HER2 antibodies include huMAb4D5-1, huMAb4D5-2, huMAb4D5-3,huMAb4D5-4, huMAb4D5-5, huMAb4D5-6, huMAb4D5-7 and huMAb4D5-8 orTrastuzumab (HERCEPTIN®) as described in Table 3 of U.S. Pat. No.5,821,337 expressly incorporated herein by reference; humanized 520C9(WO93/21319) and humanized 2C4 antibodies as described herein.

For the purposes herein, “Trastuzumab,” “HERCEPTIN®,” and “huMAb4D5-8”refer to an antibody comprising the light and heavy chain amino acidsequences in SEQ ID NOS. 13 and 14, respectively.

Herein, “Pertuzumab” and “rhuMAb 2C4,” refer to an antibody comprisingthe variable light and variable heavy amino acid sequences in SEQ IDNos. 3 and 4, respectfully. Where Pertuzumab is an intact antibody, itpreferably comprises the light chain and heavy chain amino acidsequences in SEQ ID Nos. 15 and 16, respectively.

A “naked antibody” is an antibody (as herein defined) that is notconjugated to a heterologous molecule, such as a cytotoxic moiety orradiolabel.

An “isolated” antibody is one which has been identified and separatedand/or recovered from a component of its natural environment.Contaminant components of its natural environment are materials whichwould interfere with diagnostic or therapeutic uses for the antibody,and may include enzymes, hormones, and other proteinaceous ornonproteinaceous solutes. In preferred embodiments, the antibody will bepurified (1) to greater than 95% by weight of antibody as determined bythe Lowry method, and most preferably more than 99% by weight, (2) to adegree sufficient to obtain at least 15 residues of N-terminal orinternal amino acid sequence by use of a spinning cup sequenator, or (3)to homogeneity by SDS-PAGE under reducing or nonreducing conditionsusing Coomassie blue or, preferably, silver stain. Isolated antibodyincludes the antibody in situ within recombinant cells since at leastone component of the antibody's natural environment will not be present.Ordinarily, however, isolated antibody will be prepared by at least onepurification step.

A HER2 antibody which “inhibits HER dimerization more effectively thanTrastuzumab” is one which reduces or eliminates HER dimers moreeffectively (for example at least about 2-fold more effectively) thanTrastuzumab. Preferably, such an antibody inhibits HER2 dimerization atleast about as effectively as an antibody selected from the groupconsisting of intact murine monoclonal antibody 2C4, a Fab fragment ofmurine monoclonal antibody 2C4, intact Pertuzumab, and a Fab fragment ofPertuzumab. One can evaluate HER dimerization inhibition by studying HERdimers directly, or by evaluating HER activation, or downstreamsignaling, which results from HER dimerization, and/or by evaluating theantibody-HER2 binding site, etc. Assays for screening for antibodieswith the ability to inhibit HER dimerization more effectively thanTrastuzumab are described in Agus et al. Cancer Cell 2: 127-137 (2002)and WO01/00245 (Adams et al.). By way of example only, one may assay forinhibition of HER dimerization by assessing, for example, inhibition ofHER dimer formation (see, e.g., FIG. 1A-B of Agus et al. Cancer Cell 2:127-137 (2002); and WO01/00245); reduction in HER ligand activation ofcells which express HER dimers (WO01/00245 and FIG. 2A-B of Agus et al.Cancer Cell 2: 127-137 (2002), for example); blocking of HER ligandbinding to cells which express HER dimers (WO01/00245, and FIG. 2E ofAgus et al. Cancer Cell 2: 127-137 (2002), for example); cell growthinhibition of cancer cells (e.g. MCF7, MDA-MD-134, ZR-75-1, MD-MB-175,T-47D cells) which express HER dimers in the presence (or absence) ofHER ligand (WO01/00245 and FIGS. 3A-D of Agus et al. Cancer Cell 2:127-137 (2002), for instance); inhibition of downstream signaling (forinstance, inhibition of HRG-dependent AKT phosphorylation or inhibitionof HRG- or TGFα-dependent MAPK phosphorylation) (see, WO01/00245, andFIG. 2C-D of Agus et al. Cancer Cell 2: 127-137 (2002), for example).One may also assess whether the antibody inhibits HER dimerization bystudying the antibody-HER2 binding site, for instance, by evaluating astructure or model, such as a crystal structure, of the antibody boundto HER2 (See, for example, Franklin et al. Cancer Cell 5:317-328(2004)).

The HER2 antibody may “inhibit HRG-dependent AKT phosphorylation” and/orinhibit “HRG- or TGFα-dependent MAPK phosphorylation” more effectively(for instance at least 2-fold more effectively) than Trastuzumab (seeAgus et al. Cancer Cell 2: 127-137 (2002) and WO01/00245, by way ofexample).

The HER2 antibody may be one which does “not inhibit HER2 ectodomaincleavage” (Molina et al. Cancer Res. 61:4744-4749 (2001)).

A HER2 antibody that “binds to a heterodimeric binding site” of HER2,binds to residues in domain II (and optionally also binds to residues inother of the domains of the HER2 extracellular domain, such as domains Iand III), and can sterically hinder, at least to some extent, formationof a HER2-EGFR, HER2-HER3, or HER2-HER4 heterodimer. Franklin et al.Cancer Cell 5:317-328 (2004) characterize the HER2-Pertuzumab crystalstructure, deposited with the RCSB Protein Data Bank (ID Code IS78),illustrating an exemplary antibody that binds to the heterodimericbinding site of HER2.

An antibody that “binds to domain II” of HER2 binds to residues indomain II and optionally residues in other domain(s) of HER2, such asdomains I and III.

A “growth inhibitory agent” when used herein refers to a compound orcomposition which inhibits growth of a cell, especially a HER expressingcancer cell either in vitro or in vivo. Thus, the growth inhibitoryagent may be one which significantly reduces the percentage of HERexpressing cells in S phase. Examples of growth inhibitory agentsinclude agents that block cell cycle progression (at a place other thanS phase), such as agents that induce G1 arrest and M-phase arrest.Classical M-phase blockers include the vincas (vincristine andvinblastine), taxanes, and topo II inhibitors such as doxorubicin,epirubicin, daunorubicin, etoposide, and bleomycin. Those agents thatarrest G1 also spill over into S-phase arrest, for example, DNAalkylating agents such as tamoxifen, prednisone, dacarbazine,mechlorethamine, cisplatin, methotrexate, 5-fluorouracil, and ara-C.Further information can be found in The Molecular Basis of Cancer,Mendelsohn and Israel, eds., Chapter 1, entitled “Cell cycle regulation,oncogenes, and antineoplastic drugs” by Murakami et al. (WB Saunders:Philadelphia, 1995), especially p. 13.

Examples of “growth inhibitory” antibodies are those which bind to HER2and inhibit the growth of cancer cells overexpressing HER2. Preferredgrowth inhibitory HER2 antibodies inhibit growth of SK-BR-3 breast tumorcells in cell culture by greater than 20%, and preferably greater than50% (e.g. from about 50% to about 100%) at an antibody concentration ofabout 0.5 to 30 μg/ml, where the growth inhibition is determined sixdays after exposure of the SK-BR-3 cells to the antibody (see U.S. Pat.No. 5,677,171 issued Oct. 14, 1997). The SK-BR-3 cell growth inhibitionassay is described in more detail in that patent and hereinbelow. Thepreferred growth inhibitory antibody is a humanized variant of murinemonoclonal antibody 4D5, e.g., Trastuzumab.

An antibody which “induces apoptosis” is one which induces programmedcell death as determined by binding of annexin V, fragmentation of DNA,cell shrinkage, dilation of endoplasmic reticulum, cell fragmentation,and/or formation of membrane vesicles (called apoptotic bodies). Thecell is usually one which overexpresses the HER2 receptor. Preferablythe cell is a tumor cell, e.g. a breast, ovarian, stomach, endometrial,salivary gland, lung, kidney, colon, thyroid, pancreatic or bladdercell. In vitro, the cell may be a SK-BR-3, BT474, Calu 3 cell,MDA-MB-453, MDA-MB-361 or SKOV3 cell. Various methods are available forevaluating the cellular events associated with apoptosis. For example,phosphatidyl serine (PS) translocation can be measured by annexinbinding; DNA fragmentation can be evaluated through DNA laddering; andnuclear/chromatin condensation along with DNA fragmentation can beevaluated by any increase in hypodiploid cells. Preferably, the antibodywhich induces apoptosis is one which results in about 2 to 50 fold,preferably about 5 to 50 fold, and most preferably about 10 to 50 fold,induction of annexin binding relative to untreated cell in an annexinbinding assay using BT474 cells (see below). Examples of HER2 antibodiesthat induce apoptosis are 7C2 and 7F3.

The “epitope 2C4” is the region in the extracellular domain of HER2 towhich the antibody 2C4 binds. In order to screen for antibodies whichbind to the 2C4 epitope, a routine cross-blocking assay such as thatdescribed in Antibodies, A Laboratory Manual, Cold Spring HarborLaboratory, Ed Harlow and David Lane (1988), can be performed.Alternatively, epitope mapping can be performed to assess whether theantibody binds to the 2C4 epitope of HER2 using methods known in the artand/or one can study the antibody-HER2 structure (Franklin et al. CancerCell 5:317-328 (2004)) to see what domain(s) of HER2 is/are bound by theantibody. Epitope 2C4 comprises residues from domain II in theextracellular domain of HER2. 2C4 and Pertuzumab bind to theextracellular domain of HER2 at the junction of domains I, II and III.Franklin et al. Cancer Cell 5:317-328 (2004).

The “epitope 4D5” is the region in the extracellular domain of HER2 towhich the antibody 4D5 (ATCC CRL 10463) and Trastuzumab bind. Thisepitope is close to the transmembrane domain of HER2, and within DomainIV of HER2. To screen for antibodies which bind to the 4D5 epitope, aroutine cross-blocking assay such as that described in Antibodies, ALaboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and DavidLane (1988), can be performed. Alternatively, epitope mapping can beperformed to assess whether the antibody binds to the 4D5 epitope ofHER2 (e.g. any one or more residues in the region from about residue 529to about residue 625, inclusive, in FIG. 1).

The “epitope 7C2/7F3” is the region at the N terminus, within Domain I,of the extracellular domain of HER2 to which the 7C2 and/or 7F3antibodies (each deposited with the ATCC, see below) bind. To screen forantibodies which bind to the 7C2/7F3 epitope, a routine cross-blockingassay such as that described in Antibodies, A Laboratory Manual, ColdSpring Harbor Laboratory, Ed Harlow and David Lane (1988), can beperformed. Alternatively, epitope mapping can be performed to establishwhether the antibody binds to the 7C2/7F3 epitope on HER2 (e.g. any oneor more of residues in the region from about residue 22 to about residue53 of HER2 in FIG. 1).

“Treatment” refers to both therapeutic treatment and prophylactic orpreventative measures. Those in need of treatment include those alreadywith the disease as well as those in which the disease is to beprevented. Hence, the patient to be treated herein may have beendiagnosed as having the disease or may be predisposed or susceptible tothe disease.

The terms “cancer” and “cancerous” refer to or describe thephysiological condition in mammals that is typically characterized byunregulated cell growth. Examples of cancer include, but are not limitedto, carcinoma, lymphoma, blastoma (including medulloblastoma andretinoblastoma), sarcoma (including liposarcoma and synovial cellsarcoma), neuroendocrine tumors (including carcinoid tumors, gastrinoma,and islet cell cancer), mesothelioma, schwannoma (including acousticneuroma), meningioma, adenocarcinoma, melanoma, and leukemia or lymphoidmalignancies. More particular examples of such cancers include squamouscell cancer (e.g. epithelial squamous cell cancer), lung cancerincluding small-cell lung cancer, non-small cell lung cancer,adenocarcinoma of the lung and squamous carcinoma of the lung, cancer ofthe peritoneum, hepatocellular cancer, gastric or stomach cancerincluding gastrointestinal cancer, pancreatic cancer, glioblastoma,cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma,breast cancer, colon cancer, rectal cancer, colorectal cancer,endometrial or uterine carcinoma, salivary gland carcinoma, kidney orrenal cancer, prostate cancer, vulval cancer, thyroid cancer, hepaticcarcinoma, anal carcinoma, penile carcinoma, testicular cancer,esophagael cancer, tumors of the biliary tract, as well as head and neckcancer.

The term “effective amount” refers to an amount of a drug effective totreat disease in the patient. Where the disease is cancer, the effectiveamount of the drug may reduce the number of cancer cells; reduce thetumor size; inhibit (i.e., slow to some extent and preferably stop)cancer cell infiltration into peripheral organs; inhibit (i.e., slow tosome extent and preferably stop) tumor metastasis; inhibit, to someextent, tumor growth; and/or relieve to some extent one or more of thesymptoms associated with the cancer. To the extent the drug may preventgrowth and/or kill existing cancer cells, it may be cytostatic and/orcytotoxic. The effective amount may extend progression free survival,result in an objective response (including a partial response, PR, orcomplete respose, CR), increase overall survival time, and/or improveone or more symptoms of cancer.

A “HER2 positive cancer” is one comprising cells which have HER2 proteinpresent at their cell surface.

A cancer which “overexpresses” a HER receptor is one which hassignificantly higher levels of a HER receptor, such as HER2, at the cellsurface thereof, compared to a noncancerous cell of the same tissuetype. Such overexpression may be caused by gene amplification or byincreased transcription or translation. HER receptor overexpression maybe determined in a diagnostic or prognostic assay by evaluatingincreased levels of the HER protein present on the surface of a cell(e.g. via an immunohistochemistry assay; IHC). Alternatively, oradditionally, one may measure levels of HER-encoding nucleic acid in thecell, e.g. via fluorescent in situ hybridization (FISH; see WO98/45479published October, 1998), southern blotting, or polymerase chainreaction (PCR) techniques, such as real time quantitative PCR (RT-PCR).One may also study HER receptor overexpression by measuring shed antigen(e.g., HER extracellular domain) in a biological fluid such as serum(see, e.g., U.S. Pat. No. 4,933,294 issued Jun. 12, 1990; WO91/05264published Apr. 18, 1991; U.S. Pat. No. 5,401,638 issued Mar. 28, 1995;and Sias et al. J. Immunol. Methods 132: 73-80 (1990)). Aside from theabove assays, various in vivo assays are available to the skilledpractitioner. For example, one may expose cells within the body of thepatient to an antibody which is optionally labeled with a detectablelabel, e.g. a radioactive isotope, and binding of the antibody to cellsin the patient can be evaluated, e.g. by external scanning forradioactivity or by analyzing a biopsy taken from a patient previouslyexposed to the antibody.

Conversely, a cancer which “does not overexpress HER2 receptor” is onewhich does not express higher than normal levels of HER2 receptorcompared to a noncancerous cell of the same tissue type.

A cancer which “overexpresses” a HER ligand is one which producessignificantly higher levels of that ligand compared to a noncancerouscell of the same tissue type. Such overexpression may be caused by geneamplification or by increased transcription or translation.Overexpression of the HER ligand may be determined diagnostically byevaluating levels of the ligand (or nucleic acid encoding it) in thepatient, e.g. in a tumor biopsy or by various diagnostic assays such asthe IHC, FISH, southern blotting, PCR or in vivo assays described above.

The term “cytotoxic agent” as used herein refers to a substance thatinhibits or prevents the function of cells and/or causes destruction ofcells. The term is intended to include radioactive isotopes (e.g. At²¹¹,I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, B²¹², P³² and radioactive isotopesof Lu), chemotherapeutic agents, and toxins such as small moleculetoxins or enzymatically active toxins of bacterial, fungal, plant oranimal origin, including fragments and/or variants thereof.

A “chemotherapeutic agent” is a chemical compound useful in thetreatment of cancer. Examples of chemotherapeutic agents includealkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN®);alkyl sulfonates such as busulfan, improsulfan and piposulfan;aziridines such as benzodopa, carboquone, meturedopa, and uredopa;ethylenimines and methylamelamines including altretamine,triethylenemelamine, trietylenephosphoramide,triethiylenethiophosphoramide and trimethylolomelamine; acetogenins(especially bullatacin and bullatacinone); delta-9-tetrahydrocannabinol(dronabinol, MARINOL®); beta-lapachone; lapachol; colchicines; betulinicacid; a camptothecin (including the synthetic analogue topotecan(HYCAMTIN®), CPT-11 (irinotecan, CAMPTOSAR®), acetylcamptothecin,scopolectin, and 9-aminocamptothecin); bryostatin; callystatin; CC-1065(including its adozelesin, carzelesin and bizelesin syntheticanalogues); podophyllotoxin; podophyllinic acid; teniposide;cryptophycins (particularly cryptophycin 1 and cryptophycin 8);dolastatin; duocarmycin (including the synthetic analogues, KW-2189 andCB1-TM1); eleutherobin; pancratistatin; a sarcodictyin; spongistatin;nitrogen mustards such as chlorambucil, chlomaphazine, cholophosphamide,estramustine, ifosfamide, mechlorethamine, mechlorethamine oxidehydrochloride, melphalan, novembichin, phenesterine, prednimustine,trofosfamide, uracil mustard; nitrosureas such as carmustine,chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine;antibiotics such as the enediyne antibiotics (e.g., calicheamicin,especially calicheamicin gammall and calicheamicin omegall (see, e.g.,Agnew, Chem. Intl. Ed. Engl., 33: 183-186 (1994)); dynemicin, includingdynemicin A; an esperamicin; as well as neocarzinostatin chromophore andrelated chromoprotein enediyne antiobiotic chromophores),aclacinomysins, actinomycin, authramycin, azaserine, bleomycins,cactinomycin, carabicin, caminomycin, carzinophilin, chromomycinis,dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine,doxorubicin (including ADRIAMYCIN®, morpholino-doxorubicin,cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin, doxorubicin HClliposome injection (DOXIL®), liposomal doxorubicin TLC D-99 (MYOCET®),peglylated liposomal doxorubicin (CAELYX®), and deoxydoxorubicin),epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins such asmitomycin C, mycophenolic acid, nogalamycin, olivomycins, peplomycin,potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin,streptozocin, tubercidin, ubenimex, zinostatin, zorubicin;anti-metabolites such as methotrexate, gemcitabine (GEMZAR®), tegafur(UFTORAL®), capecitabine (XELODA®), an epothilone, and 5-fluorouracil(5-FU); folic acid analogues such as denopterin, methotrexate,pteropterin, trimetrexate; purine analogs such as fludarabine,6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such asancitabine, azacitidine, 6-azauridine, carmofur, cytarabine,dideoxyuridine, doxifluridine, enocitabine, floxuridine; anti-adrenalssuch as aminoglutethimide, mitotane, trilostane; folic acid replenishersuch as frolinic acid; aceglatone; aldophosphamide glycoside;aminolevulinic acid; eniluracil; amsacrine; bestrabucil; bisantrene;edatraxate; defofamine; demecolcine; diaziquone; elfornithine;elliptinium acetate; etoglucid; gallium nitrate; hydroxyurea; lentinan;lonidainine; maytansinoids such as maytansine and ansamitocins;mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin;phenamet; pirarubicin; losoxantrone; 2-ethylhydrazide; procarbazine;PSK® polysaccharide complex (JHS Natural Products, Eugene, Oreg.);razoxane; rhizoxin; sizofuran; spirogermanium; tenuazonic acid;triaziquone; 2,2′,2″-trichlorotriethylamine; trichothecenes (especiallyT-2 toxin, verracurin A, roridin A and anguidine); urethan; dacarbazine;mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine;arabinoside (“Ara-C”); thiotepa; taxoid, e.g., paclitaxel (TAXOL®),albumin-engineered nanoparticle formulation of paclitaxel (ABRAXANE™),and docetaxel (TAXOTERE®); chloranbucil; 6-thioguanine; mercaptopurine;methotrexate; platinum agents such as cisplatin, oxaliplatin, andcarboplatin; vincas, which prevent tubulin polymerization from formingmicrotubules, including vinblastine (VELBAN®), vincristine (ONCOVIN®),vindesine (ELDISINE®, FILDESIN®), and vinorelbine (NAVELBINE®);etoposide (VP-16); ifosfamide; mitoxantrone; leucovovin; novantrone;edatrexate; daunomycin; aminopterin; ibandronate; topoisomeraseinhibitor RFS 2000; difluoromethylomithine (DMFO); retinoids such asretinoic acid, including bexarotene (TARGRETIN®); bisphosphonates suchas clodronate (for example, BONEFOS® or OSTAC®), etidronate (DIDROCAL®),NE-58095, zoledronic acid/zoledronate (ZOMETA®), alendronate (FOSAMAX®),pamidronate (AREDIA®), tiludronate (SKELID®), or risedronate (ACTONEL®);troxacitabine (a 1,3-dioxolane nucleoside cytosine analog); antisenseoligonucleotides, particularly those that inhibit expression of genes insignaling pathways implicated in aberrant cell proliferation, such as,for example, PKC-alpha, Raf, H-Ras, and epidermal growth factor receptor(EGF-R); vaccines such as THERATOPE® vaccine and gene therapy vaccines,for example, ALLOVECTIN® vaccine, LEUVECTIN® vaccine, and VAXID®vaccine; topoisomerase 1 inhibitor (e.g., LURTOTECAN®); rmRH (e.g.,ABARELIX®); BAY439006 (sorafenib; Bayer); SU-11248 (Pfizer); perifosine,COX-2 inhibitor (e.g. celecoxib or etoricoxib), proteosome inhibitor(e.g. PS341); bortezomib (VELCADE®); CCI-779; tipifarnib (R11577);orafenib, ABT510; Bcl-2 inhibitor such as oblimersen sodium(GENASENSE®); pixantrone; EGFR inhibitors (see definition below);tyrosine kinase inhibitors (see definition below); and pharmaceuticallyacceptable salts, acids or derivatives of any of the above; as well ascombinations of two or more of the above such as CHOP, an abbreviationfor a combined therapy of cyclophosphamide, doxorubicin, vincristine,and prednisolone, and FOLFOX, an abbreviation for a treatment regimenwith oxaliplatin (ELOXATIN™) combined with 5-FU and leucovovin.

Also included in this definition are anti-hormonal agents that act toregulate or inhibit hormone action on tumors such as anti-estrogens withmixed agonist/antagonist profile, including, tamoxifen (NOLVADEX®),4-hydroxytamoxifen, toremifene (FARESTON®), idoxifene, droloxifene,raloxifene (EVISTA®), trioxifene, keoxifene, and selective estrogenreceptor modulators (SERMs) such as SERM3; pure anti-estrogens withoutagonist properties, such as fulvestrant (FASLODEX®), and EM800 (suchagents may block estrogen receptor (ER) dimerization, inhibit DNAbinding, increase ER turnover, and/or suppress ER levels); aromataseinhibitors, including steroidal aromatase inhibitors such as formestaneand exemestane (AROMASIN®), and nonsteroidal aromatase inhibitors suchas anastrazole (ARIMIDEX®), letrozole (FEMARA®) and aminoglutethimide,and other aromatase inhibitors including vorozole (RIVISOR®), megestrolacetate (MEGASE®), fadrozole, imidazole; lutenizing hormone-releasinghormone agonists, including leuprolide (LUPRON® and ELIGARD®),goserelin, buserelin, and tripterelin; sex steroids, includingprogestines such as megestrol acetate and medroxyprogesterone acetate,estrogens such as diethylstilbestrol and premarin, andandrogens/retinoids such as fluoxymesterone, all transretionic acid andfenretinide; onapristone; anti-progesterones; estrogen receptordown-regulators (ERDs); anti-androgens such as flutamide, nilutamide andbicalutamide; testolactone; and pharmaceutically acceptable salts, acidsor derivatives of any of the above; as well as combinations of two ormore of the above.

As used herein, the term “EGFR-targeted drug” refers to a therapeuticagent that binds to EGFR and, optionally, inhibits EGFR activation.Examples of such agents include antibodies and small molecules that bindto EGFR. Examples of antibodies which bind to EGFR include MAb 579 (ATCCCRL HB 8506), MAb 455 (ATCC CRL HB8507), MAb 225 (ATCC CRL 8508), MAb528 (ATCC CRL 8509) (see, U.S. Pat. No. 4,943,533, Mendelsohn et al.)and variants thereof, such as chimerized 225 (C225 or Cetuximab;ERBUTIX®) and reshaped human 225 (H225) (see, WO 96/40210, ImcloneSystems Inc.); IMC-11F8, a fully human, EGFR-targeted antibody(Imclone); antibodies that bind type II mutant EGFR (U.S. Pat. No.5,212,290); humanized and chimeric antibodies that bind EGFR asdescribed in U.S. Pat. No. 5,891,996; and human antibodies that bindEGFR, such as ABX-EGF or Panitumumab (see WO98/50433, Abgenix/Amgen);EMD 55900 (Stragliotto et al Eur. J. Cancer 32A:636-640 (1996)); EMD7200(matuzumab) a humanized EGFR antibody directed against EGFR thatcompetes with both EGF and TGF-alpha for EGFR binding (EMD/Merck); humanEGFR antibody, HuMax-EGFR (GenMab); fully human antibodies known asE1.1, E2.4, E2.5, E6.2, E6.4, E2.11, E6.3 and E7.6.3 and described inU.S. Pat. No. 6,235,883; MDX-447 (Medarex Inc); and mAb 806 or humanizedmAb 806 (Johns et al., J. Biol. Chem. 279(29):30375-30384 (2004)). Theanti-EGFR antibody may be conjugated with a cytotoxic agent, thusgenerating an immunoconjugate (see, e.g., EP659,439A2, Merck PatentGmbH). EGFR antagonists include small molecules such as compoundsdescribed in U.S. Pat. Nos. 5,616,582, 5,457,105, 5,475,001, 5,654,307,5,679,683, 6,084,095, 6,265,410, 6,455,534, 6,521,620, 6,596,726,6,713,484, 5,770,599, 6,140,332, 5,866,572, 6,399,602, 6,344,459,6,602,863, 6,391,874, 6,344,455, 5,760,041, 6,002,008, and 5,747,498, aswell as the following PCT publications: WO98/14451, WO98/50038,WO99/09016, and WO99/24037. Particular small molecule EGFR antagonistsinclude OSI-774 (CP-358774, erlotinib, TARCEVA® Genentech/OSIPharmaceuticals); PD 183805 (CI 1033, 2-propenamide,N-[4-[(3-chloro-4-fluorophenyl)amino]-7-[3-(4-morpholinyl)propoxy]-6-quinazolinyl]-,dihydrochloride, Pfizer Inc.); ZD1839, gefitinib (IRESSA®)4-(3′-Chloro-4′-fluoroanilino)-7-methoxy-6-(3-morpholinopropoxy)quinazoline,AstraZeneca); ZM 105180 ((6-amino-4-(3-methylphenyl-amino)-quinazoline,Zeneca); BIBX-1382(N-8-(3-chloro-4-fluoro-phenyl)-N2-(1-methyl-piperidin-4-yl)-pyrimido[5,4-d]pyrimidine-2,8-diamine,Boehringer Ingelheim); PKI-166((R)-4-[4-[(1-phenylethyl)amino]-1H-pyrrolo[2,3-d]pyrimidin-6-yl]-phenol);(R)-6-(4-hydroxyphenyl)-4-[(1-phenylethyl)amino]-7H-pyrrolo[2,3-d]pyrimidine);CL-387785 (N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide);EKB-569(N-[4-[(3-chloro-4-fluorophenyl)amino]-3-cyano-7-ethoxy-6-quinolinyl]-4-(dimethylamino)-2-butenamide)(Wyeth); AG1478 (Sugen); AG1571 (SU 5271; Sugen); dual EGFR/HER2tyrosine kinase inhibitors such as lapatinib (GW 572016 orN-[3-chloro-4-[(3 fluorophenyl)methoxy]phenyl]6[5[[[2-methylsulfonyl)ethyl]amino]methyl]-2-furanyl]-4-quinazolinamine;Glaxo-SmithKline) or cyanoguanidine quinazoline and cyanoamidinequinazolamine derivatives.

A “tyrosine kinase inhibitor” is a molecule which inhibits tyrosinekinase activity of a tyrosine kinase such as a HER receptor. Examples ofsuch inhibitors include the EGFR-targeted drugs noted in the precedingparagraph; small molecule HER2 tyrosine kinase inhibitor such as TAK165available from Takeda; CP-724,714, an oral selective inhibitor of theErbB2 receptor tyrosine kinase (Pfizer and OSI); dual-HER inhibitorssuch as EKB-569 (available from Wyeth) which preferentially binds EGFRbut inhibits both HER2 and EGFR-overexpressing cells; lapatinib(GW572016; available from Glaxo-SmithKline) an oral HER2 and EGFRtyrosine kinase inhibitor; PKI-166 (available from Novartis); pan-HERinhibitors such as canertinib (CI-1033; Pharmacia); Raf-1 inhibitorssuch as antisense agent ISIS-5132 available from ISIS Pharmaceuticalswhich inhibits Raf-1 signaling; non-HER targeted TK inhibitors such asImatinib mesylate (GLEEVAC_(C)) available from Glaxo; MAPK extracellularregulated kinase I inhibitor CI-1040 (available from Pharmacia);quinazolines, such as PD 153035, 4-(3-chloroanilino) quinazoline;pyridopyrimidines; pyrimidopyrimidines; pyrrolopyrimidines, such as CGP59326, CGP 60261 and CGP 62706; pyrazolopyrimidines,4-(phenylamino)-7H-pyrrolo[2,3-d]pyrimidines; curcumin (diferuloylmethane, 4,5-bis(4-fluoroanilino)phthalimide); tyrphostines containingnitrothiophene moieties; PD-0183805 (Wamer-Lamber); antisense molecules(e.g. those that bind to HER-encoding nucleic acid); quinoxalines (U.S.Pat. No. 5,804,396); tryphostins (U.S. Pat. No. 5,804,396); ZD6474(Astra Zeneca); PTK-787 (Novartis/Schering AG); pan-HER inhibitors suchas CI-1033 (Pfizer); Affinitac (ISIS 3521; Isis/Lilly); Imatinibmesylate (Gleevac; Novartis); PKI 166 (Novartis); GW2016 (GlaxoSmithKline); CI-1033 (Pfizer); EKB-569 (Wyeth); Semaxinib (Sugen);ZD6474 (AstraZeneca); PTK-787 (Novartis/Schering AG); INC-1C11(Imclone); cyanoguanidine quinazoline and cyanoamidine quinazolaminederivatives; or as described in any of the following patentpublications: U.S. Pat. No. 5,804,396; WO99/09016 (American Cyanamid);WO98/43960 (American Cyanamid); WO97/38983 (Warner Lambert); WO99/06378(Warner Lambert); WO99/06396 (Warner Lambert); WO96/30347 (Pfizer, Inc);WO96/33978 (Zeneca); WO96/3397 (Zeneca); WO96/33980 (Zeneca); andUS2005/0101617.

An “anti-angiogenic agent” refers to a compound which blocks, orinterferes with to some degree, the development of blood vessels. Theanti-angiogenic factor may, for instance, be a small molecule orantibody that binds to a growth factor or growth factor receptorinvolved in promoting angiogenesis. The preferred anti-angiogenic factorherein is an antibody that binds to Vascular Endothelial Growth Factor(VEGF), such as Bevacizumab (AVASTIN®).

The term “cytokine” is a generic term for proteins released by one cellpopulation which act on another cell as intercellular mediators.Examples of such cytokines are lymphokines, monokines, and traditionalpolypeptide hormones. Included among the cytokines are growth hormonesuch as human growth hormone, N-methionyl human growth hormone, andbovine growth hormone; parathyroid hormone; thyroxine; insulin;proinsulin; relaxin; prorelaxin; glycoprotein hormones such as folliclestimulating hormone (FSH), thyroid stimulating hormone (TSH), andluteinizing hormone (LH); hepatic growth factor; fibroblast growthfactor; prolactin; placental lactogen; tumor necrosis factor-α and -β;mullerian-inhibiting substance; mouse gonadotropin-associated peptide;inhibin; activin; vascular endothelial growth factor; integrin;thrombopoietin (TPO); nerve growth factors such as NGF-β;platelet-growth factor; transforming growth factors (TGFs) such as TGF-αand TGF-β; insulin-like growth factor-I and -II; erythropoietin (EPO);osteoinductive factors; interferons such as interferon-α, -β, and -γ;colony stimulating factors (CSFs) such as macrophage-CSF (M-CSF);granulocyte-macrophage-CSF (GM-CSF); and granulocyte-CSF (G-CSF);interleukins (ILs) such as IL-1, IL-1α, IL-2, IL-3, IL-4, IL-5, IL-6,IL-7, IL-8, IL-9, IL-10, IL-11, IL-12; a tumor necrosis factor such asTNF-α or TNF-β; and other polypeptide factors including LIF and kitligand (KL). As used herein, the term cytokine includes proteins fromnatural sources or from recombinant cell culture and biologically activeequivalents of the native sequence cytokines.

II. HER2 Antibody Variant Compositions

The present invention concerns, at least in part, certain HER2 antibodycompositions. Preferably, the HER2 antibody (either or both of the mainspecies HER2 antibody and antibody variant thereof) is one which bindsto Domain II of HER2, inhibits HER dimerization more effectively thanTrastuzumab, and/or binds to a heterodimeric binding site of HER2. Thepreferred embodiment herein of the main species antibody is onecomprising the variable light and variable heavy amino acid sequences inSEQ ID Nos. 3 and 4, and most preferably comprising the light chain andheavy chain amino acid sequences in SEQ ID Nos. 15 and 16 (Pertuzumab).

The composition herein comprises a main species HER2 antibody that bindsto domain II of HER2, and acidic variants thereof wherein the acidicvariants include one, two, or three of glycated variant, disulfidereduced variant, and non-reducible variant. The acidic variants in thecomposition may include one, two, three, four, or five of glycatedvariant, deamidated variant, disulfide reduced variant, sialylatedvariant, and non-reducible variant. Preferably, the total amount of allacidic variants in the composition is less than about 25%. In oneembodiment, the glycated variant, deamidated variant, disulfide reducedvariant, sialylated variant, and non-reducible variant constitute atleast about 75-80% of the acidic variants in the composition.

The invention additionally concerns a composition comprising a mainspecies HER2 antibody comprising variable light and variable heavysequences in SEQ ID Nos. 3 and 4, respectively, and acidic variants ofthe main species antibody, wherein the acidic variants include one, two,three, four, or five of glycated variant, deamidated variant, disulfidereduced variant, sialylated variant, and non-reducible variant.

The invention provides a method of making a pharmaceutical compositioncomprising: (1) preparing a composition comprising a main species HER2antibody that binds to domain II of HER2, and acidic variants thereofincluding glycated variant, disulfide reduced variant, or non-reduciblevariant, and (2) evaluating the acidic variants in the composition, andconfirming that the amount thereof is less than about 25%. The methodcontemplates combining the composition before, during, or after step (2)with a pharmaceutically acceptable carrier. In one embodiment, thecomposition evaluated in step (2) is in a pharmaceutically acceptablecarrier.

In one embodiment, at least about 75-80% of the acidic variants(constituting the less than about 25% of the composition) are selectedfrom: glycated variant, deamidated variant, disulfide reduced variant,sialylated variant, and non-reducible variant.

The acidic variants may be evaluated by a variety of methods, butpreferably such methods include one, two, three, four, or five of: ionexchange chromatography (IEC) wherein the composition is treated withsialidase before, after, and/or during the IEC (e.g. to evaluatesialylated variant), reduced CE-SDS (e.g. to evaluate disulfide reducedvariant), non-reduced CE-SDS (e.g to evaluate non-reducible variant),boronate chromatography (e.g. to evaluate glycated variant), and peptidemapping (e.g. to evaluate deamidated variant).

In one embodiment, the overall acidic variants are evaluated by ionexchange chromatography, for example using a weak cation exchangerand/or cation exchanger with carboxylate functional group (for example,using a DIONEX PROPAC™ WCX-10 chromatography column). In one embodimentof such chromatography the conditions for the chromatography involveBuffer A of 20 mM BisTris, pH 6.0; Buffer B of 20 mM BisTris, 200 mMNaCl, pH 6.0; and a gradient of 0.5% Buffer B at 1.0 mL/min.

The composition optionally includes an amino-terminal leader extensionvariant. Preferably, the amino-terminal leader extension is on a lightchain of the antibody variant (e.g. on one or two light chains of theantibody variant). The main species HER2 antibody or the antibodyvariant may be an intact antibody or antibody fragment (e.g. Fab ofF(ab′)₂ fragments), but preferably both are intact antibodies. Theantibody variant herein may comprise an amino-terminal leader extensionon any one or more of the heavy or light chains thereof. Preferably, theamino-terminal leader extension is on one or two light chains of theantibody. The amino-terminal leader extension preferably comprises orconsists of VHS-. Presence of the amino-terminal leader extension in thecomposition can be detected by various analytical techniques including,but not limited to, N-terminal sequence analysis, assay for chargeheterogeneity (for instance, cation exchange chromatography or capillaryzone electrophoresis), mass spectrometry, etc. The amount of theantibody variant in the composition generally ranges from an amount thatconstitutes the lower detection limit of any assay (preferably cationexchange analysis) used to detect the variant to an amount less than theamount of the main species antibody. Generally, about 20% or less (e.g.from about 1% to about 15%, for instance from 5% to about 15%, andpreferably from about 8% to about 12%) of the antibody molecules in thecomposition comprise an amino-terminal leader extension. Such percentageamounts are preferably determined using cation exchange analysis.

Further amino acid sequence alterations of the main species antibodyand/or variant are contemplated, including but not limited to anantibody comprising a C-terminal lysine residue on one or both heavychains thereof (such an antibody variant may be present in an amountfrom about 1% to about 20%), antibody with one or more oxidizedmethionine residues (for example, Pertuzumab comprising oxidizedmet-254) etc.

Moreover, aside from the sialylated variant discussed above, the mainspecies antibody or variant may comprise additional glycosylationvariations, non-limiting examples of which include antibody comprising aG1 or G2 oligosaccharide structure attached to the Fc region thereof,antibody comprising a carbohydrate moiety attached to a light chainthereof (e.g. one or two carbohydrate moieties, such as glucose orgalactose, attached to one or two light chains of the antibody, forinstance attached to one or more lysine residues), antibody comprisingone or two non-glycosylated heavy chains, etc.

Optionally, the antibody comprising one or two light chains, whereineither or both of the light chains comprise the amino acid sequence inSEQ ID No. 23 (including variants thereof such as those disclosedherein). The antibody further comprises one or two heavy chains, whereineither or both of the heavy chains comprise the amino acid sequence inSEQ ID NO. 16 or SEQ ID NO. 24 (including variants thereof such as thosedisclosed herein).

The composition may be recovered from a genetically engineered cellline, e.g. a Chinese Hamster Ovary (CHO) cell line expressing the HER2antibody, or may be prepared by peptide synthesis.

III. Production of HER2 Antibodies

A description follows as to exemplary techniques for the production ofthe antibodies used in accordance with the present invention. The HER2antigen to be used for production of antibodies may be, e.g., a solubleform of the extracellular domain of HER2 or a portion thereof,containing the desired epitope. Alternatively, cells expressing HER2 attheir cell surface (e.g. NIH-3T3 cells transformed to overexpress HER2;or a carcinoma cell line such as SK-BR-3 cells, see Stancovski et al.PNAS (USA) 88:8691-8695 (1991)) can be used to generate antibodies.Other forms of HER2 useful for generating antibodies will be apparent tothose skilled in the art.

(i) Monoclonal Antibodies

Monoclonal antibodies are obtained from a population of substantiallyhomogeneous antibodies, i.e., the individual antibodies comprising thepopulation are identical and/or bind the same epitope, except forpossible variants that may arise during production of the monoclonalantibody, such as those variants described herein. Thus, the modifier“monoclonal” indicates the character of the antibody as not being amixture of discrete antibodies.

For example, the monoclonal antibodies may be made using the hybridomamethod first described by Kohler et al., Nature, 256:495 (1975), or maybe made by recombinant DNA methods (U.S. Pat. No. 4,816,567).

In the hybridoma method, a mouse or other appropriate host animal, suchas a hamster, is immunized as hereinabove described to elicitlymphocytes that produce or are capable of producing antibodies thatwill specifically bind to the protein used for immunization.Alternatively, lymphocytes may be immunized in vitro. Lymphocytes thenare fused with myeloma cells using a suitable fusing agent, such aspolyethylene glycol, to form a hybridoma cell (Goding, MonoclonalAntibodies: Principles and Practice, pp. 59-103 (Academic Press, 1986)).

The hybridoma cells thus prepared are seeded and grown in a suitableculture medium that preferably contains one or more substances thatinhibit the growth or survival of the unfused, parental myeloma cells.For example, if the parental myeloma cells lack the enzyme hypoxanthineguanine phosphoribosyl transferase (HGPRT or HPRT), the culture mediumfor the hybridomas typically will include hypoxanthine, aminopterin, andthymidine (HAT medium), which substances prevent the growth ofHGPRT-deficient cells.

Preferred myeloma cells are those that fuse efficiently, support stablehigh-level production of antibody by the selected antibody-producingcells, and are sensitive to a medium such as HAT medium. Among these,preferred myeloma cell lines are murine myeloma lines, such as thosederived from MOPC-21 and MPC-11 mouse tumors available from the SalkInstitute Cell Distribution Center, San Diego, Calif. USA, and SP-2 orX63-Ag8-653 cells available from the American Type Culture Collection,Rockville, Md. USA. Human myeloma and mouse-human heteromyeloma celllines also have been described for the production of human monoclonalantibodies (Kozbor, J. Immunol., 133:3001 (1984); and Brodeur et al.,Monoclonal Antibody Production Techniques and Applications, pp. 51-63(Marcel Dekker, Inc., New York, 1987)).

Culture medium in which hybridoma cells are growing is assayed forproduction of monoclonal antibodies directed against the antigen.Preferably, the binding specificity of monoclonal antibodies produced byhybridoma cells is determined by immunoprecipitation or by an in vitrobinding assay, such as radioimmunoassay (RIA) or enzyme-linkedimmunoabsorbent assay (ELISA).

The binding affinity of the monoclonal antibody can, for example, bedetermined by the Scatchard analysis of Munson et al., Anal. Biochem.,107:220 (1980).

After hybridoma cells are identified that produce antibodies of thedesired specificity, affinity, and/or activity, the clones may besubcloned by limiting dilution procedures and grown by standard methods(Goding, Monoclonal Antibodies: Principles and Practice, pp. 59-103(Academic Press, 1986)). Suitable culture media for this purposeinclude, for example, D-MEM or RPMI-1640 medium. In addition, thehybridoma cells may be grown in vivo as ascites tumors in an animal.

The monoclonal antibodies secreted by the subclones are suitablyseparated from the culture medium, ascites fluid, or serum byconventional antibody purification procedures such as, for example,protein A-Sepharose, hydroxylapatite chromatography, gelelectrophoresis, dialysis, or affinity chromatography.

DNA encoding the monoclonal antibodies is readily isolated and sequencedusing conventional procedures (e.g., by using oligonucleotide probesthat are capable of binding specifically to genes encoding the heavy andlight chains of murine antibodies). The hybridoma cells serve as apreferred source of such DNA. Once isolated, the DNA may be placed intoexpression vectors, which are then transfected into host cells such asE. coli cells, simian COS cells, Chinese Hamster Ovary (CHO) cells, ormyeloma cells that do not otherwise produce antibody protein, to obtainthe synthesis of monoclonal antibodies in the recombinant host cells.Review articles on recombinant expression in bacteria of DNA encodingthe antibody include Skerra et al., Curr. Opinion in Immunol., 5:256-262(1993) and Plückthun, Immunol. Revs., 130:151-188 (1992).

In a further embodiment, monoclonal antibodies or antibody fragments canbe isolated from antibody phage libraries generated using the techniquesdescribed in McCafferty et al., Nature, 348:552-554 (1990). Clackson etal., Nature, 352:624-628 (1991) and Marks et al., J. Mol. Biol.,222:581-597 (1991) describe the isolation of murine and humanantibodies, respectively, using phage libraries. Subsequent publicationsdescribe the production of high affinity (nM range) human antibodies bychain shuffling (Marks et al., Bio/Technology, 10:779-783 (1992)), aswell as combinatorial infection and in vivo recombination as a strategyfor constructing very large phage libraries (Waterhouse et al., Nuc.Acids. Res., 21:2265-2266 (1993)). Thus, these techniques are viablealternatives to traditional monoclonal antibody hybridoma techniques forisolation of monoclonal antibodies.

The DNA also may be modified, for example, by substituting the codingsequence for human heavy chain and light chain constant domains in placeof the homologous murine sequences (U.S. Pat. No. 4,816,567; andMorrison, et al., Proc. Natl. Acad. Sci. USA, 81:6851 (1984)), or bycovalently joining to the immunoglobulin coding sequence all or part ofthe coding sequence for a non-immunoglobulin polypeptide.

Typically such non-immunoglobulin polypeptides are substituted for theconstant domains of an antibody, or they are substituted for thevariable domains of one antigen-combining site of an antibody to createa chimeric bivalent antibody comprising one antigen-combining sitehaving specificity for an antigen and another antigen-combining sitehaving specificity for a different antigen.

(ii) Humanized Antibodies

Methods for humanizing non-human antibodies have been described in theart. Preferably, a humanized antibody has one or more amino acidresidues introduced into it from a source which is non-human. Thesenon-human amino acid residues are often referred to as “import”residues, which are typically taken from an “import” variable domain.Humanization can be essentially performed following the method of Winterand co-workers (Jones et al., Nature, 321:522-525 (1986); Riechmann etal., Nature, 332:323-327 (1988); Verhoeyen et al., Science,239:1534-1536 (1988)), by substituting hypervariable region sequencesfor the corresponding sequences of a human antibody. Accordingly, such“humanized” antibodies are chimeric antibodies (U.S. Pat. No. 4,816,567)wherein substantially less than an intact human variable domain has beensubstituted by the corresponding sequence from a non-human species. Inpractice, humanized antibodies are typically human antibodies in whichsome hypervariable region residues and possibly some FR residues aresubstituted by residues from analogous sites in rodent antibodies.

The choice of human variable domains, both light and heavy, to be usedin making the humanized antibodies is very important to reduceantigenicity. According to the so-called “best-fit” method, the sequenceof the variable domain of a rodent antibody is screened against theentire library of known human variable-domain sequences. The humansequence which is closest to that of the rodent is then accepted as thehuman framework region (FR) for the humanized antibody (Sims et al., J.Immunol., 151:2296 (1993); Chothia et al., J. Mol. Biol., 196:901(1987)). Another method uses a particular framework region derived fromthe consensus sequence of all human antibodies of a particular subgroupof light or heavy chains. The same framework may be used for severaldifferent humanized antibodies (Carter et al., Proc. Natl. Acad. Sci.USA, 89:4285 (1992); Presta et al., J. Immunol., 151:2623 (1993)).

It is further important that antibodies be humanized with retention ofhigh affinity for the antigen and other favorable biological properties.To achieve this goal, according to a preferred method, humanizedantibodies are prepared by a process of analysis of the parentalsequences and various conceptual humanized products usingthree-dimensional models of the parental and humanized sequences.Three-dimensional immunoglobulin models are commonly available and arefamiliar to those skilled in the art. Computer programs are availablewhich illustrate and display probable three-dimensional conformationalstructures of selected candidate immunoglobulin sequences. Inspection ofthese displays permits analysis of the likely role of the residues inthe functioning of the candidate immuunoglobulin sequence, i.e., theanalysis of residues that influence the ability of the candidateimmunoglobulin to bind its antigen. In this way, FR residues can beselected and combined from the recipient and import sequences so thatthe desired antibody characteristic, such as increased affinity for thetarget antigen(s), is achieved. In general, the hypervariable regionresidues are directly and most substantially involved in influencingantigen binding.

U.S. Pat. No. 6,949,245 describes production of exemplary humanized HER2antibodies which bind HER2 and block ligand activation of a HERreceptor. The humanized antibody of particular interest herein blocksEGF, TGF-α and/or HRG mediated activation of MAPK essentially aseffectively as intact murine monoclonal antibody 2C4 (or a Fab fragmentthereof) and/or binds HER2 essentially as effectively as intact murinemonoclonal antibody 2C4 (or a Fab fragment thereof). The humanizedantibody herein may, for example, comprise nonhuman hypervariable regionresidues incorporated into a human variable heavy domain and may furthercomprise a framework region (FR) substitution at a position selectedfrom the group consisting of 69H, 71H and 73H utilizing the variabledomain numbering system set forth in Kabat et al., Sequences of Proteinsof Immunological Interest, 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, Md. (1991). In one embodiment, thehumanized antibody comprises FR substitutions at two or all of positions69H, 71H and 73H.

An exemplary humanized antibody of interest herein comprises variableheavy complementarity determining residues GFTFTDYTMX, where X ispreferrably D or S (SEQ ID NO:7); DVNPNSGGSIYNQRFKG (SEQ ID NO:8);and/or NLGPSFYFDY (SEQ ID NO:9), optionally comprising amino acidmodifications of those CDR residues, e.g. where the modificationsessentially maintain or improve affinity of the antibody. For example,the antibody variant of interest may have from about one to about sevenor about five amino acid substitutions in the above variable heavy CDRsequences. Such antibody variants may be prepared by affinitymaturation, e.g., as described below. The most preferred humanizedantibody comprises the variable heavy amino acid sequence in SEQ IDNO:4.

The humanized antibody may comprise variable light complementaritydetermining residues KASQDVSIGVA (SEQ ID NO: 10); SASYX¹X²X³, where X¹is preferably R or L, X² is preferably Y or E, and X³ is preferably T orS (SEQ ID NO: 11); and/or QQYYIYPYT (SEQ ID NO:12), e.g. in addition tothose variable heavy domain CDR residues in the preceding paragraph.Such humanized antibodies optionally comprise amino acid modificationsof the above CDR residues, e.g. where the modifications essentiallymaintain or improve affinity of the antibody. For example, the antibodyvariant of interest may have from about one to about seven or about fiveamino acid substitutions in the above variable light CDR sequences. Suchantibody variants may be prepared by affinity maturation, e.g., asdescribed below. The most preferred humanized antibody comprises thevariable light amino acid sequence in SEQ ID NO:3.

The present application also contemplates affinity matured antibodieswhich bind HER2 and block ligand activation of a HER receptor. Theparent antibody may be a human antibody or a humanized antibody, e.g.,one comprising the variable light and/or variable heavy sequences of SEQID Nos. 3 and 4, respectively (i.e. variant 574). The affinity maturedantibody preferably binds to HER2 receptor with an affinity superior tothat of intact murine 2C4 or intact variant 574 (e.g. from about two orabout four fold, to about 100 fold or about 1000 fold improved affinity,e.g. as assessed using a HER2-extracellular domain (ECD) ELISA).Exemplary variable heavy CDR residues for substitution include H28, H30,H34, H35, H64, H96, H99, or combinations of two or more (e.g. two,three, four, five, six, or seven of these residues). Examples ofvariable light CDR residues for alteration include L28, L50, L53, L56,L91, L92, L93, L94, L96, L97 or combinations of two or more (e.g. two tothree, four, five or up to about ten of these residues).

Various forms of the humanized antibody or affinity matured antibody arecontemplated. For example, the humanized antibody or affinity maturedantibody may be an antibody fragment, such as a Fab, which is optionallyconjugated with one or more cytotoxic agent(s) in order to generate animmunoconjugate. Alternatively, the humanized antibody or affinitymatured antibody may be an intact antibody, such as an intact IgG1antibody.

(iii) Human Antibodies

As an alternative to humanization, human antibodies can be generated.For example, it is now possible to produce transgenic animals (e.g.,mice) that are capable, upon immunization, of producing a fullrepertoire of human antibodies in the absence of endogenousimmunoglobulin production. For example, it has been described that thehomozygous deletion of the antibody heavy-chain joining region (J_(H))gene in chimeric and germ-line mutant mice results in completeinhibition of endogenous antibody production. Transfer of the humangerm-line immunoglobulin gene array in such germ-line mutant mice willresult in the production of human antibodies upon antigen challenge.See, e.g., Jakobovits et al., Proc. Natl. Acad. Sci. USA, 90:2551(1993); Jakobovits et al., Nature, 362:255-258 (1993); Bruggermann etal., Year in Immuno., 7:33 (1993); and U.S. Pat. Nos. 5,591,669,5,589,369 and 5,545,807.

Alternatively, phage display technology (McCafferty et al., Nature348:552-553 (1990)) can be used to produce human antibodies and antibodyfragments in vitro, from immunoglobulin variable (V) domain generepertoires from unimmunized donors. According to this technique,antibody V domain genes are cloned in-frame into either a major or minorcoat protein gene of a filamentous bacteriophage, such as M13 or fd, anddisplayed as functional antibody fragments on the surface of the phageparticle. Because the filamentous particle contains a single-strandedDNA copy of the phage genome, selections based on the functionalproperties of the antibody also result in selection of the gene encodingthe antibody exhibiting those properties. Thus, the phage mimics some ofthe properties of the B-cell. Phage display can be performed in avariety of formats; for their review see, e.g., Johnson, Kevin S. andChiswell, David J., Current Opinion in Structural Biology 3:564-571(1993). Several sources of V-gene segments can be used for phagedisplay. Clackson et al., Nature, 352:624-628 (1991) isolated a diversearray of anti-oxazolone antibodies from a small random combinatoriallibrary of V genes derived from the spleens of immunized mice. Arepertoire of V genes from unimmunized human donors can be constructedand antibodies to a diverse array of antigens (including self-antigens)can be isolated essentially following the techniques described by Markset al., J. Mol. Biol. 222:581-597 (1991), or Griffith et al., EMBO J.12:725-734 (1993). See, also, U.S. Pat. Nos. 5,565,332 and 5,573,905.

Human antibodies may also be generated by in vitro activated B cells(see U.S. Pat. Nos. 5,567,610 and 5,229,275).

Human HER2 antibodies are described in U.S. Pat. No. 5,772,997 issuedJun. 30, 1998 and WO 97/00271 published Jan. 3, 1997.

(iv) Antibody Fragments

Various techniques have been developed for the production of antibodyfragments. Traditionally, these fragments were derived via proteolyticdigestion of intact antibodies (see, e.g., Morimoto et al., Journal ofBiochemical and Biophysical Methods 24:107-117 (1992); and Brennan etal., Science, 229:81 (1985)). However, these fragments can now beproduced directly by recombinant host cells. For example, the antibodyfragments can be isolated from the antibody phage libraries discussedabove. Alternatively, Fab′-SH fragments can be directly recovered fromE. coli and chemically coupled to form F(ab′)₂ fragments (Carter et al.,Bio/Technology 10: 163-167 (1992)). According to another approach,F(ab′)₂ fragments can be isolated directly from recombinant host cellculture. Other techniques for the production of antibody fragments willbe apparent to the skilled practitioner. In other embodiments, theantibody of choice is a single chain Fv fragment (scFv). See WO93/16185; U.S. Pat. No. 5,571,894; and U.S. Pat. No. 5,587,458. Theantibody fragment may also be a “linear antibody”, e.g., as described inU.S. Pat. No. 5,641,870 for example. Such linear antibody fragments maybe monospecific or bispecific.

(v) Bispecific Antibodies

Bispecific antibodies are antibodies that have binding specificities forat least two different epitopes. Exemplary bispecific antibodies maybind to two different epitopes of the HER2 protein. Other suchantibodies may combine a HER2 binding site with binding site(s) forEGFR, HER3 and/or HER4. Alternatively, a HER2 arm may be combined withan arm which binds to a triggering molecule on a leukocyte such as aT-cell receptor molecule (e.g. CD2 or CD3), or Fc receptors for IgG(FcγR), such as FcγRI (CD64), FcγRII (CD32) and FcγRIII (CD 16) so as tofocus cellular defense mechanisms to the HER2-expressing cell.Bispecific antibodies may also be used to localize cytotoxic agents tocells which express HER2. These antibodies possess a HER2-binding armand an arm which binds the cytotoxic agent (e.g. saporin,anti-interferon-α, vinca alkaloid, ricin A chain, methotrexate orradioactive isotope hapten). Bispecific antibodies can be prepared asfull length antibodies or antibody fragments (e.g. F(ab′)₂ bispecificantibodies).

WO 96/16673 describes a bispecific HER2/FcγRIII antibody and U.S. Pat.No. 5,837,234 discloses a bispecific HER2/FcγRI antibody IDM1 (Osidem).A bispecific HER2/Fcα antibody is shown in WO98/02463. U.S. Pat. No.5,821,337 teaches a bispecific HER2/CD3 antibody. MDX-210 is abispecific HER2-FcγRIII Ab.

Methods for making bispecific antibodies are known in the art.Traditional production of full length bispecific antibodies is based onthe coexpression of two immunoglobulin heavy chain-light chain pairs,where the two chains have different specificities (Millstein et al.,Nature, 305:537-539 (1983)). Because of the random assortment ofimmunoglobulin heavy and light chains, these hybridomas (quadromas)produce a potential mixture of 10 different antibody molecules, of whichonly one has the correct bispecific structure. Purification of thecorrect molecule, which is usually done by affinity chromatographysteps, is rather cumbersome, and the product yields are low. Similarprocedures are disclosed in WO 93/08829, and in Traunecker et al., EMBOJ., 10:3655-3659 (1991).

According to a different approach, antibody variable domains with thedesired binding specificities (antibody-antigen combining sites) arefused to immunoglobulin constant domain sequences. The fusion preferablyis with an immunoglobulin heavy chain constant domain, comprising atleast part of the hinge, CH2, and CH3 regions. It is preferred to havethe first heavy-chain constant region (CH1) containing the sitenecessary for light chain binding, present in at least one of thefusions. DNAs encoding the immunoglobulin heavy chain fusions and, ifdesired, the immunoglobulin light chain, are inserted into separateexpression vectors, and are co-transfected into a suitable hostorganism. This provides for great flexibility in adjusting the mutualproportions of the three polypeptide fragments in embodiments whenunequal ratios of the three polypeptide chains used in the constructionprovide the optimum yields. It is, however, possible to insert thecoding sequences for two or all three polypeptide chains in oneexpression vector when the expression of at least two polypeptide chainsin equal ratios results in high yields or when the ratios are of noparticular significance.

In a preferred embodiment of this approach, the bispecific antibodiesare composed of a hybrid immunoglobulin heavy chain with a first bindingspecificity in one arm, and a hybrid immunoglobulin heavy chain-lightchain pair (providing a second binding specificity) in the other arm. Itwas found that this asymmetric structure facilitates the separation ofthe desired bispecific compound from unwanted immunoglobulin chaincombinations, as the presence of an immunoglobulin light chain in onlyone half of the bispecific molecule provides for a facile way ofseparation. This approach is disclosed in WO 94/04690. For furtherdetails of generating bispecific antibodies see, for example, Suresh etal., Methods in Enzymology, 121:210 (1986).

According to another approach described in U.S. Pat. No. 5,731,168, theinterface between a pair of antibody molecules can be engineered tomaximize the percentage of heterodimers which are recovered fromrecombinant cell culture. The preferred interface comprises at least apart of the C_(H)3 domain of an antibody constant domain. In thismethod, one or more small amino acid side chains from the interface ofthe first antibody molecule are replaced with larger side chains (e.g.tyrosine or tryptophan). Compensatory “cavities” of identical or similarsize to the large side chain(s) are created on the interface of thesecond antibody molecule by replacing large amino acid side chains withsmaller ones (e.g. alanine or threonine). This provides a mechanism forincreasing the yield of the heterodimer over other unwanted end-productssuch as homodimers.

Bispecific antibodies include cross-linked or “heteroconjugate”antibodies. For example, one of the antibodies in the heteroconjugatecan be coupled to avidin, the other to biotin. Such antibodies have, forexample, been proposed to target immune system cells to unwanted cells(U.S. Pat. No. 4,676,980), and for treatment of HIV infection (WO91/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may bemade using any convenient cross-linking methods. Suitable cross-linkingagents are well known in the art, and are disclosed in U.S. Pat. No.4,676,980, along with a number of cross-linking techniques.

Techniques for generating bispecific antibodies from antibody fragmentshave also been described in the literature. For example, bispecificantibodies can be prepared using chemical linkage. Brennan et al.,Science, 229: 81 (1985) describe a procedure wherein intact antibodiesare proteolytically cleaved to generate F(ab′)₂ fragments. Thesefragments are reduced in the presence of the dithiol complexing agentsodium arsenite to stabilize vicinal dithiols and prevent intermoleculardisulfide formation. The Fab′ fragments generated are then converted tothionitrobenzoate (TNB) derivatives. One of the Fab′-TNB derivatives isthen reconverted to the Fab′-thiol by reduction with mercaptoethylamineand is mixed with an equimolar amount of the other Fab′-TNB derivativeto form the bispecific antibody. The bispecific antibodies produced canbe used as agents for the selective immobilization of enzymes.

Recent progress has facilitated the direct recovery of Fab′-SH fragmentsfrom E. coli, which can be chemically coupled to form bispecificantibodies. Shalaby et al., J. Exp. Med., 175: 217-225 (1992) describethe production of a fully humanized bispecific antibody F(ab′)₂molecule. Each Fab′ fragment was separately secreted from E. coli andsubjected to directed chemical coupling in vitro to form the bispecificantibody. The bispecific antibody thus formed was able to bind to cellsoverexpressing the HER2 receptor and normal human T cells, as well astrigger the lytic activity of human cytotoxic lymphocytes against humanbreast tumor targets.

Various techniques for making and isolating bispecific antibodyfragments directly from recombinant cell culture have also beendescribed. For example, bispecific antibodies have been produced usingleucine zippers. Kostelny et al., J. Immunol., 148(5): 1547-1553 (1992).The leucine zipper peptides from the Fos and Jun proteins were linked tothe Fab′ portions of two different antibodies by gene fusion. Theantibody homodimers were reduced at the hinge region to form monomersand then re-oxidized to form the antibody heterodimers. This method canalso be utilized for the production of antibody homodimers. The“diabody” technology described by Hollinger et al., Proc. Natl. Acad.Sci. USA, 90:6444-6448 (1993) has provided an alternative mechanism formaking bispecific antibody fragments. The fragments comprise aheavy-chain variable domain (V_(H)) connected to a light-chain variabledomain (V_(L)) by a linker which is too short to allow pairing betweenthe two domains on the same chain. Accordingly, the V_(H) and V_(L)domains of one fragment are forced to pair with the complementary V_(L)and V_(H) domains of another fragment, thereby forming twoantigen-binding sites. Another strategy for making bispecific antibodyfragments by the use of single-chain Fv (sFv) dimers has also beenreported. See Gruber et al., J. Immunol., 152:5368 (1994).

Antibodies with more than two valencies are contemplated. For example,trispecific antibodies can be prepared. Tutt et al. J. Immunol. 147: 60(1991).

(vi) Other Amino Acid Sequence Modifications

Amino acid sequence modification(s) of the HER2 antibodies describedherein are contemplated. For example, it may be desirable to improve thebinding affinity and/or other biological properties of the antibody.Amino acid sequence variants of the HER2 antibody are prepared byintroducing appropriate nucleotide changes into the HER2 antibodynucleic acid, or by peptide synthesis. Such modifications include, forexample, deletions from, and/or insertions into and/or substitutions of,residues within the amino acid sequences of the HER2 antibody. Anycombination of deletion, insertion, and substitution is made to arriveat the final construct, provided that the final construct possesses thedesired characteristics. The amino acid changes also may alterpost-translational processes of the HER2 antibody, such as changing thenumber or position of glycosylation sites.

A useful method for identification of certain residues or regions of theHER2 antibody that are preferred locations for mutagenesis is called“alanine scanning mutagenesis” as described by Cunningham and WellsScience, 244:1081-1085 (1989). Here, a residue or group of targetresidues are identified (e.g., charged residues such as arg, asp, his,lys, and glu) and replaced by a neutral or negatively charged amino acid(most preferably alanine or polyalanine) to affect the interaction ofthe amino acids with HER2 antigen. Those amino acid locationsdemonstrating functional sensitivity to the substitutions then arerefined by introducing further or other variants at, or for, the sitesof substitution. Thus, while the site for introducing an amino acidsequence variation is predetermined, the nature of the mutation per seneed not be predetermined. For example, to analyze the performance of amutation at a given site, ala scanning or random mutagenesis isconducted at the target codon or region and the expressed HER2 antibodyvariants are screened for the desired activity.

Amino acid sequence insertions include amino- and/or carboxyl-terminalfusions ranging in length from one residue to polypeptides containing ahundred or more residues, as well as intrasequence insertions of singleor multiple amino acid residues. Examples of terminal insertions includea HER2 antibody with an N-terminal methionyl residue or the antibodyfused to a cytotoxic polypeptide. Other insertional variants of the HER2antibody molecule include the fusion to the N- or C-terminus of the HER2antibody to an enzyme (e.g. for ADEPT) or a polypeptide which increasesthe serum half-life of the antibody.

Another type of variant is an amino acid substitution variant. Thesevariants have at least one amino acid residue in the HER2 antibodymolecule replaced by a different residue. The sites of greatest interestfor substitutional mutagenesis include the hypervariable regions orCDRs, but FR or Fc region alterations are also contemplated.Conservative substitutions are shown in Table 1 under the heading of“preferred substitutions”. If such substitutions result in a change inbiological activity, then more substantial changes, denominated“exemplary substitutions” in Table 1, or as further described below inreference to amino acid classes, may be introduced and the productsscreened.

TABLE 1 Original Exemplary Preferred Residue Substitutions SubstitutionsAla (A) Val; Leu; Ile Val Arg (R) Lys; Gln; Asn Lys Asn (N) Gln; His;Asp, Lys; Arg Gln Asp (D) Glu; Asn Glu Cys (C) Ser; Ala Ser Gln (Q) Asn;Glu Asn Glu (E) Asp; Gln Asp Gly (G) Ala Ala His (H) Asn; Gln; Lys; ArgArg Ile (I) Leu; Val; Met; Ala; Leu Phe; Norleucine Leu (L) Norleucine;Ile; Val; Ile Met; Ala; Phe Lys (K) Arg; Gln; Asn Arg Met (M) Leu; Phe;Ile Leu Phe (F) Trp; Leu; Val; Ile; Ala; Tyr Tyr Pro (P) Ala Ala Ser (S)Thr Thr Thr (T) Val; Ser Ser Trp (W) Tyr; Phe Tyr Tyr (Y) Trp; Phe; Thr;Ser Phe Val (V) Ile; Leu; Met; Phe; Leu Ala; Norleucine

Substantial modifications in the biological properties of the antibodyare accomplished by selecting substitutions that differ significantly intheir effect on maintaining (a) the structure of the polypeptidebackbone in the area of the substitution, for example, as a sheet orhelical conformation, (b) the charge or hydrophobicity of the moleculeat the target site, or (c) the bulk of the side chain. Amino acids maybe grouped according to similarities in the properties of their sidechains (in A. L. Lehninger, in Biochemistry, second ed., pp. 73-75,Worth Publishers, New York (1975)):

(1) non-polar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp(W), Met (M)

(2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn(N), Gln (Q)

(3) acidic: Asp (D), Glu (E)

(4) basic: Lys (K), Arg (R), His (H)

Alternatively, naturally occurring residues may be divided into groupsbased on common side-chain properties:

(1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile;

(2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln;

(3) acidic: Asp, Glu;

(4) basic: His, Lys, Arg;

(5) residues that influence chain orientation: Gly, Pro;

(6) aromatic: Trp, Tyr, Phe.

Non-conservative substitutions will entail exchanging a member of one ofthese classes for another class.

Any cysteine residue not involved in maintaining the proper conformationof the HER2 antibody also may be substituted, generally with serine, toimprove the oxidative stability of the molecule and prevent aberrantcrosslinking. Conversely, cysteine bond(s) may be added to the antibodyto improve its stability (particularly where the antibody is an antibodyfragment such as an Fv fragment).

A particularly preferred type of substitutional variant involvessubstituting one or more hypervariable region residues of a parentantibody (e.g. a humanized or human antibody). Generally, the resultingvariant(s) selected for further development will have improvedbiological properties relative to the parent antibody from which theyare generated. A convenient way for generating such substitutionalvariants involves affinity maturation using phage display. Briefly,several hypervariable region sites (e.g. 6-7 sites) are mutated togenerate all possible amino substitutions at each site. The antibodyvariants thus generated are displayed in a monovalent fashion fromfilamentous phage particles as fusions to the gene III product of M13packaged within each particle. The phage-displayed variants are thenscreened for their biological activity (e.g. binding affinity) as hereindisclosed. In order to identify candidate hypervariable region sites formodification, alanine scanning mutagenesis can be performed to identifyhypervariable region residues contributing significantly to antigenbinding. Alternatively, or additionally, it may be beneficial to analyzea crystal structure of the antigen-antibody complex to identify contactpoints between the antibody and huma HER2. Such contact residues andneighboring residues are candidates for substitution according to thetechniques elaborated herein. Once such variants are generated, thepanel of variants is subjected to screening as described herein andantibodies with superior properties in one or more relevant assays maybe selected for further development.

Another type of amino acid variant of the antibody alters the originalglycosylation pattern of the antibody. By altering is meant deleting oneor more carbohydrate moieties found in the antibody, and/or adding oneor more glycosylation sites that are not present in the antibody.

Glycosylation of antibodies is typically either N-linked or O-linked.N-linked refers to the attachment of the carbohydrate moiety to the sidechain of an asparagine residue. The tripeptide sequencesasparagine-X-serine and asparagine-X-threonine, where X is any aminoacid except proline, are the recognition sequences for enzymaticattachment of the carbohydrate moiety to the asparagine side chain.Thus, the presence of either of these tripeptide sequences in apolypeptide creates a potential glycosylation site. O-linkedglycosylation refers to the attachment of one of the sugarsN-aceylgalactosamine, galactose, or xylose to a hydroxyamino acid, mostcommonly serine or threonine, although 5-hydroxyproline or5-hydroxylysine may also be used.

Addition of glycosylation sites to the antibody is convenientlyaccomplished by altering the amino acid sequence such that it containsone or more of the above-described tripeptide sequences (for N-linkedglycosylation sites). The alteration may also be made by the additionof, or substitution by, one or more serine or threonine residues to thesequence of the original antibody (for O-linked glycosylation sites).

Where the antibody comprises an Fc region, any oligosaccharide structureattached thereto may be altered. For example, antibodies with a maturecarbohydrate structure that lacks fucose attached to an Fc region of theantibody are described in US Pat Appl No US 2003/0157108 A1, Presta, L.See also US 2004/0093621 A1 (Kyowa Hakko Kogyo Co., Ltd). Antibodieswith a bisecting N-acetylglucosamine (GlcNAc) in the oligosaccharidestructure attached to an Fc region of the antibody are referenced inWO03/011878, Jean-Mairet et al. and U.S. Pat. No. 6,602,684, Umana etal. Antibodies with at least one galactose residue in an oligosaccharidestructure attached to an Fc region of the antibody are reported inWO97/30087, Patel et al. See, also, WO98/58964 (Raju, S.) and WO99/22764(Raju, S.) concerning antibodies with altered carbohydrate attached tothe Fc region thereof. Antibody compositions comprising main speciesantibody with such carbohydrate structures attached to one or two heavychains of the Fc region are contemplated herein.

Nucleic acid molecules encoding amino acid sequence variants of the HER2antibody are prepared by a variety of methods known in the art. Thesemethods include, but are not limited to, isolation from a natural source(in the case of naturally occurring amino acid sequence variants) orpreparation by oligonucleotide-mediated (or site-directed) mutagenesis,PCR mutagenesis, and cassette mutagenesis of an earlier prepared variantor a non-variant version of the HER2 antibody.

(vii) Screening for Antibodies with the Desired Properties

Techniques for generating antibodies have been described above. One mayfurther select antibodies with certain biological characteristics, asdesired.

To identify an antibody which blocks ligand activation of a HERreceptor, the ability of the antibody to block HER ligand binding tocells expressing the HER receptor (e.g. in conjugation with another HERreceptor with which the HER receptor of interest forms a HERhetero-oligomer) may be determined. For example, cells naturallyexpressing, or transfected to express, HER receptors of the HERhetero-oligomer may be incubated with the antibody and then exposed tolabeled HER ligand. The ability of the HER2 antibody to block ligandbinding to the HER receptor in the HER hetero-oligomer may then beevaluated.

For example, inhibition of HRG binding to MCF7 breast tumor cell linesby HER2 antibodies may be performed using monolayer MCF7 cultures on icein a 24-well-plate format essentially as described in WO01/00245. HER2monoclonal antibodies may be added to each well and incubated for 30minutes. ¹²⁵I-labeled rHRGβ1₁₇₇₋₂₂₄ (25 pm) may then be added, and theincubation may be continued for 4 to 16 hours. Dose response curves maybe prepared and an IC₅₀ value may be calculated for the antibody ofinterest. In one embodiment, the antibody which blocks ligand activationof an HER receptor will have an IC₅₀ for inhibiting HRG binding to MCF7cells in this assay of about 50 nM or less, more preferably 10 nM orless. Where the antibody is an antibody fragment such as a Fab fragment,the IC₅₀ for inhibiting HRG binding to MCF7 cells in this assay may, forexample, be about 100 nM or less, more preferably 50 nM or less.

Alternatively, or additionally, the ability of the HER2 antibody toblock HER ligand-stimulated tyrosine phosphorylation of a HER receptorpresent in a HER hetero-oligomer may be assessed. For example, cellsendogenously expressing the HER receptors or transfected to expressedthem may be incubated with the antibody and then assayed for HERligand-dependent tyrosine phosphorylation activity using ananti-phosphotyrosine monoclonal (which is optionally conjugated with adetectable label). The kinase receptor activation assay described inU.S. Pat. No. 5,766,863 is also available for determining HER receptoractivation and blocking of that activity by an antibody.

In one embodiment, one may screen for an antibody which inhibits HRGstimulation of p180 tyrosine phosphorylation in MCF7 cells essentiallyas described in WO01/00245. For example, the MCF7 cells may be plated in24-well plates and monoclonal antibodies to HER2 may be added to eachwell and incubated for 30 minutes at room temperature; thenrHRGβ1₁₇₇₋₂₄₄ may be added to each well to a final concentration of 0.2nM, and the incubation may be continued for 8 minutes. Media may beaspirated from each well, and reactions may be stopped by the additionof 100 μl of SDS sample buffer (5% SDS, 25 mM DTT, and 25 mM Tris-HCl,pH 6.8). Each sample (25 μl) may be electrophoresed on a 4-12% gradientgel (Novex) and then electrophoretically transferred to polyvinylidenedifluoride membrane. Antiphosphotyrosine (at 1 g/mil) immunoblots may bedeveloped, and the intensity of the predominant reactive band atM_(r)˜180,000 may be quantified by reflectance densitometry. Theantibody selected will preferably significantly inhibit HRG stimulationof p180 tyrosine phosphorylation to about 0-35% of control in thisassay. A dose-response curve for inhibition of HRG stimulation of p180tyrosine phosphorylation as determined by reflectance densitometry maybe prepared and an IC₅₀ for the antibody of interest may be calculated.In one embodiment, the antibody which blocks ligand activation of a HERreceptor will have an IC₅₀ for inhibiting HRG stimulation of p180tyrosine phosphorylation in this assay of about 50 nM or less, morepreferably 10 nM or less. Where the antibody is an antibody fragmentsuch as a Fab fragment, the IC₅₀ for inhibiting HRG stimulation of p180tyrosine phosphorylation in this assay may, for example, be about 100 nMor less, more preferably 50 nM or less.

One may also assess the growth inhibitory effects of the antibody onMDA-MB-175 cells, e.g, essentially as described in Schaefer et al.Oncogene 15:1385-1394 (1997). According to this assay, MDA-MB-175 cellsmay treated with a HER2 monoclonal antibody (10 μg/mL) for 4 days andstained with crystal violet. Incubation with a HER2 antibody may show agrowth inhibitory effect on this cell line similar to that displayed bymonoclonal antibody 2C4. In a further embodiment, exogenous HRG will notsignificantly reverse this inhibition. Preferably, the antibody will beable to inhibit cell proliferation of MDA-MB-175 cells to a greaterextent than monoclonal antibody 4D5 (and optionally to a greater extentthan monoclonal antibody 7F3), both in the presence and absence ofexogenous HRG.

In one embodiment, the HER2 antibody of interest may block heregulindependent association of HER2 with HER3 in both MCF7 and SK-BR-3 cellsas determined in a co-immunoprecipitation experiment such as thatdescribed in WO01/00245 substantially more effectively than monoclonalantibody 4D5, and preferably substantially more effectively thanmonoclonal antibody 7F3.

To identify growth inhibitory HER2 antibodies, one may screen forantibodies which inhibit the growth of cancer cells which overexpressHER2. In one embodiment, the growth inhibitory antibody of choice isable to inhibit growth of SK-BR-3 cells in cell culture by about 20-100%and preferably by about 50-100% at an antibody concentration of about0.5 to 30 μg/ml. To identify such antibodies, the SK-BR-3 assaydescribed in U.S. Pat. No. 5,677,171 can be performed. According to thisassay, SK-BR-3 cells are grown in a 1:1 mixture of F12 and DMEM mediumsupplemented with 10% fetal bovine serum, glutamine and penicillinstreptomycin. The SK-BR-3 cells are plated at 20,000 cells in a 35 mmcell culture dish (2 mls/35 mm dish). 0.5 to 30 μg/ml of the HER2antibody is added per dish. After six days, the number of cells,compared to untreated cells are counted using an electronic COULTER™cell counter. Those antibodies which inhibit growth of the SK-BR-3 cellsby about 20-100% or about 50-100% may be selected as growth inhibitoryantibodies. See U.S. Pat. No. 5,677,171 for assays for screening forgrowth inhibitory antibodies, such as 4D5 and 3E8.

In order to select for antibodies which induce apoptosis, an annexinbinding assay using BT474 cells is available. The BT474 cells arecultured and seeded in dishes as discussed in the preceding paragraph.The medium is then removed and replaced with fresh medium alone ormedium containing 10 μg/ml of the monoclonal antibody. Following a threeday incubation period, monolayers are washed with PBS and detached bytrypsinization. Cells are then centrifuged, resuspended in Ca₂₊ bindingbuffer and aliquoted into tubes as discussed above for the cell deathassay. Tubes then receive labeled annexin (e.g. annexin V-FTIC) (1μg/ml). Samples may be analyzed using a FACSCAN™ flow cytometer andFACSCONVERT™ CellQuest software (Becton Dickinson). Those antibodieswhich induce statistically significant levels of annexin bindingrelative to control are selected as apoptosis-inducing antibodies. Inaddition to the annexin binding assay, a DNA staining assay using BT474cells is available. In order to perform this assay, BT474 cells whichhave been treated with the antibody of interest as described in thepreceding two paragraphs are incubated with 9 μg/ml HOECHST 33342 for 2hr at 37° C., then analyzed on an EPICS ELITE™ flow cytometer (CoulterCorporation) using MODFIT LT™ software (Verity Software House).Antibodies which induce a change in the percentage of apoptotic cellswhich is 2 fold or greater (and preferably 3 fold or greater) thanuntreated cells (up to 100% apoptotic cells) may be selected aspro-apoptotic antibodies using this assay. See WO98/17797 for assays forscreening for antibodies which induce apoptosis, such as 7C2 and 7F3.

To screen for antibodies which bind to an epitope on HER2 bound by anantibody of interest, a routine cross-blocking assay such as thatdescribed in Antibodies, A Laboratory Manual, Cold Spring HarborLaboratory, Ed Harlow and David Lane (1988), can be performed to assesswhether the antibody cross-blocks binding of an antibody, such as 2C4 orPertuzumab, to HER2. Alternatively, or additionally, epitope mapping canbe performed by methods known in the art and/or one can study theantibody-HER2 structure (Franklin et al. Cancer Cell 5:317-328 (2004))to see what domain(s) of HER2 is/are bound by the antibody.

(viii) Immunoconjugates

The invention also pertains to immunoconjugates comprising an antibodyconjugated to a cytotoxic agent such as a chemotherapeutic agent, toxin(e.g. a small molecule toxin or an enzymatically active toxin ofbacterial, fungal, plant or animal origin, including fragments and/orvariants thereof), or a radioactive isotope (i.e., a radioconjugate).

Chemotherapeutic agents useful in the generation of suchimmunoconjugates have been described above. Conjugates of an antibodyand one or more small molecule toxins, such as a calicheamicin, amaytansine (U.S. Pat. No. 5,208,020), a trichothene, and CC1065 are alsocontemplated herein.

In one preferred embodiment of the invention, the antibody is conjugatedto one or more maytansine molecules (e.g. about 1 to about 10 maytansinemolecules per antibody molecule). Maytansine may, for example, beconverted to May-SS-Me which may be reduced to May-SH3 and reacted withmodified antibody (Chari et al. Cancer Research 52: 127-131 (1992)) togenerate a maytansinoid-antibody immunoconjugate.

Another immunoconjugate of interest comprises a HER2 antibody conjugatedto one or more calicheamicin molecules. The calicheamicin family ofantibiotics are capable of producing double-stranded DNA breaks atsub-picomolar concentrations. Structural analogues of calicheamicinwhich may be used include, but are not limited to, γ₁ ^(I), α₂ ^(I), α₃^(I), N-acetyl-γ₁ ^(I), PSAG and θ^(I) ₁ (Hinman et al. Cancer Research53: 3336-3342 (1993) and Lode et al. Cancer Research 58: 2925-2928(1998)). See, also, U.S. Pat. Nos. 5,714,586; 5,712,374; 5,264,586; and5,773,001 expressly incorporated herein by reference.

Enzymatically active toxins and fragments thereof which can be usedinclude diphtheria A chain, nonbinding active fragments of diphtheriatoxin, exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain,abrin A chain, modeccin A chain, alpha-sarcin, Aleurites fordiiproteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII,and PAP-S), momordica charantia inhibitor, curcin, crotin, sapaonariaofficinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin,enomycin and the tricothecenes. See, for example, WO 93/21232 publishedOct. 28, 1993.

The present invention further contemplates an immunoconjugate formedbetween an antibody and a compound with nucleolytic activity (e.g. aribonuclease or a DNA endonuclease such as a deoxyribonuclease; DNase).

A variety of radioactive isotopes are available for the production ofradioconjugated HER2 antibodies. Examples include At²¹¹, I¹³¹, I¹²⁵,Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, Bi²¹², P³² and radioactive isotopes of Lu.

Conjugates of the antibody and cytotoxic agent may be made using avariety of bifunctional protein coupling agents such asN-succinimidyl-3-(2-pyridyldithiol) propionate (SPDP),succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate,iminothiolane (IT), bifunctional derivatives of imidoesters (such asdimethyl adipimidate HCL), active esters (such as disuccinimidylsuberate), aldehydes (such as glutareldehyde), bis-azido compounds (suchas bis(p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (suchas bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astolyene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin canbe prepared as described in Vitetta et al. Science 238: 1098 (1987).Carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent forconjugation of radionucleotide to the antibody. See WO94/11026. Thelinker may be a “cleavable linker” facilitating release of the cytotoxicdrug in the cell. For example, an acid-labile linker,peptidase-sensitive linker, dimethyl linker or disulfide-containinglinker (Chari et al. Cancer Research 52: 127-131 (1992)) may be used.

Alternatively, a fusion protein comprising the HER2 antibody andcytotoxic agent may be made, e.g. by recombinant techniques or peptidesynthesis.

In yet another embodiment, the antibody may be conjugated to a“receptor” (such streptavidin) for utilization in tumor pretargetingwherein the antibody-receptor conjugate is administered to the patient,followed by removal of unbound conjugate from the circulation using aclearing agent and then administration of a “ligand” (e.g. avidin) whichis conjugated to a cytotoxic agent (e.g. a radionucleotide).

(ix) Other Antibody Modifications

Other modifications of the antibody are contemplated herein. Forexample, the antibody may be linked to one of a variety ofnonproteinaceous polymers, e.g., polyethylene glycol, polypropyleneglycol, polyoxyalkylenes, or copolymers of polyethylene glycol andpolypropylene glycol. The antibody also may be entrapped inmicrocapsules prepared, for example, by coacervation techniques or byinterfacial polymerization (for example, hydroxymethylcellulose orgelatin-microcapsules and poly-(methylmethacylate) microcapsules,respectively), in colloidal drug delivery systems (for example,liposomes, albumin microspheres, microemulsions, nano-particles andnanocapsules), or in macroemulsions. Such techniques are disclosed inRemington's Pharmaceutical Sciences, 16th edition, Oslo, A., Ed.,(1980).

It may be desirable to modify the antibody of the invention with respectto effector function, e.g. so as to enhance antigen-dependentcell-mediated cyotoxicity (ADCC) and/or complement dependentcytotoxicity (CDC) of the antibody. This may be achieved by introducingone or more amino acid substitutions in an Fc region of the antibody.Alternatively or additionally, cysteine residue(s) may be introduced inthe Fc region, thereby allowing interchain disulfide bond formation inthis region. The homodimeric antibody thus generated may have improvedinternalization capability and/or increased complement-mediated cellkilling and antibody-dependent cellular cytotoxicity (ADCC). See Caronet al., J. Exp Med. 176:1191-1195 (1992) and Shopes, B. J. Immunol.148:2918-2922 (1992). Homodimeric antibodies with enhanced anti-tumoractivity may also be prepared using heterobifunctional cross-linkers asdescribed in Wolff et al. Cancer Research 53:2560-2565 (1993).Alternatively, an antibody can be engineered which has dual Fc regionsand may thereby have enhanced complement lysis and ADCC capabilities.See Stevenson et al. Anti-Cancer Drug Design 3:219-230 (1989).

WO00/42072 (Presta, L.) describes antibodies with improved ADCC functionin the presence of human effector cells, where the antibodies compriseamino acid substitutions in the Fc region thereof. Preferably, theantibody with improved ADCC comprises substitutions at positions 298,333, and/or 334 of the Fc region. Preferably the altered Fc region is ahuman IgG1 Fc region comprising or consisting of substitutions at one,two or three of these positions.

Antibodies with altered C1q binding and/or complement dependentcytotoxicity (CDC) are described in WO99/51642, U.S. Pat. No.6,194,551B1, U.S. Pat. No. 6,242,195B1, U.S. Pat. No. 6,528,624B1 andU.S. Pat. No. 6,538,124 (Idusogie et al.). The antibodies comprise anamino acid substitution at one or more of amino acid positions 270, 322,326, 327, 329, 313, 333 and/or 334 of the Fc region thereof.

To increase the serum half life of the antibody, one may incorporate asalvage receptor binding epitope into the antibody (especially anantibody fragment) as described in U.S. Pat. No. 5,739,277, for example.As used herein, the term “salvage receptor binding epitope” refers to anepitope of the Fc region of an IgG molecule (e.g., IgG₁, IgG₂, IgG₃, orIgG₄) that is responsible for increasing the in vivo serum half-life ofthe IgG molecule. Antibodies with substitutions in an Fc region thereofand increased serum half-lives are also described in WO00/42072 (Presta,L.).

Engineered antibodies with three or more (preferably four) functionalantigen binding sites are also contemplated (US Appln No. US2002/0004587A1, Miller et al.).

The HER2 antibodies disclosed herein may also be formulated asimmunoliposomes. Liposomes containing the antibody are prepared bymethods known in the art, such as described in Epstein et al., Proc.Natl. Acad. Sci. USA, 82:3688 (1985); Hwang et al., Proc. Natl. Acad.Sci. USA, 77:4030 (1980); U.S. Pat. Nos. 4,485,045 and 4,544,545; andWO97/38731 published Oct. 23, 1997. Liposomes with enhanced circulationtime are disclosed in U.S. Pat. No. 5,013,556.

Particularly useful liposomes can be generated by the reverse phaseevaporation method with a lipid composition comprisingphosphatidylcholine, cholesterol and PEG-derivatizedphosphatidylethanolamine (PEG-PE). Liposomes are extruded throughfilters of defined pore size to yield liposomes with the desireddiameter. Fab′ fragments of the antibody of the present invention can beconjugated to the liposomes as described in Martin et al. J. Biol. Chem.257: 286-288 (1982) via a disulfide interchange reaction. Achemotherapeutic agent is optionally contained within the liposome. SeeGabizon et al. J. National Cancer Inst. 81(19)1484 (1989).

IV. Pharmaceutical Formulations

Therapeutic formulations of the compositions of the present inventionare prepared for storage by mixing the composition with optionalpharmaceutically acceptable carriers, excipients or stabilizers(Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)),in the form of lyophilized formulations or aqueous solutions. Acceptablecarriers, excipients, or stabilizers are nontoxic to recipients at thedosages and concentrations employed, and include buffers such asphosphate, citrate, and other organic acids; antioxidants includingascorbic acid and methionine; preservatives (such asoctadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride; phenol, butyl or benzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecularweight (less than about 10 residues) polypeptides; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, histidine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates including glucose, mannose, ordextrins; chelating agents such as EDTA; sugars such as sucrose,mannitol, trehalose or sorbitol; salt-forming counter-ions such assodium; metal complexes (e.g. Zn-protein complexes); and/or non-ionicsurfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG).Lyophilized HER2 antibody formulations are described in WO 97/04801.Particularly preferred formulations for the present composition aredescribed in US20006/088523.

The formulation herein may also contain more than one active compound asnecessary for the particular indication being treated, preferably thosewith complementary activities that do not adversely affect each other.For example, it may be desirable to further provide antibodies whichbind to EGFR, HER2 (e.g. an antibody which binds a different epitope onHER2), HER3, HER4, or vascular endothelial factor (VEGF) in the oneformulation. Alternatively, or additionally, the composition may furthercomprise a chemotherapeutic agent, cytotoxic agent, cytokine, growthinhibitory agent, anti-hormonal agent, EGFR-targeted drug,anti-angiogenic agent, tyrosine kinase inhibitor, and/orcardioprotectant. Such molecules are suitably present in combination inamounts that are effective for the purpose intended.

The active ingredients may also be entrapped in microcapsules prepared,for example, by coacervation techniques or by interfacialpolymerization, for example, hydroxymethylcellulose orgelatin-microcapsules and poly-(methylmethacylate) microcapsules,respectively, in colloidal drug delivery systems (for example,liposomes, albumin microspheres, microemulsions, nano-particles andnanocapsules) or in macroemulsions. Such techniques are disclosed inRemington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980).

Sustained-release preparations may be prepared. Suitable examples ofsustained-release preparations include semipermeable matrices of solidhydrophobic polymers containing the antibody, which matrices are in theform of shaped articles, e.g. films, or microcapsules. Examples ofsustained-release matrices include polyesters, hydrogels (for example,poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides(U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and γethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradablelactic acid-glycolic acid copolymers such as the LUPRON DEPOT™(injectable microspheres composed of lactic acid-glycolic acid copolymerand leuprolide acetate), and poly-D-(−)-3-hydroxybutyric acid.

The formulations to be used for in vivo administration must be sterile.This is readily accomplished by filtration through sterile filtrationmembranes.

V. Treatment with the HER2 Antibody Composition

It is contemplated that, according to the present invention, the HER2antibody may be used to treat cancer. The cancer will generally be HER2positive, such that the HER2 antibody herein is able to bind to thecancer cells. In one embodiment, the cancer expresses low HER3 (e.g.ovarian cancer) or has elevated HER2:HER3 ratio (e.g. ovarian cancer).Various cancers that can be treated with the composition are listed inthe definitions section above.

Preferred cancers to be treated herein include: breast cancer, includingHER2 positive breast cancer, optionally in combination with trastuzumaband a taxoid such as docetaxel, and including neoadjuvant therapy ofbreast cancer; ovarian cancer (including both platinum-resistant andplatinum-sensitive ovarian cancer) (see US2006/0013819, for example);lung cancer (including non small cell lung cancer, NSCLC), optionally incombination with an EGFR inhibitor (see US 2007/0020261 for example);colorectal cancer, etc.

It is also contemplated that the HER2 antibody may be used to treatvarious non-malignant diseases or disorders, such as autoimmune disease(e.g. psoriasis); endometriosis; scleroderma; restenosis; polyps such ascolon polyps, nasal polyps or gastrointestinal polyps; fibroadenoma;respiratory disease; cholecystitis; neurofibromatosis; polycystic kidneydisease; inflammatory diseases; skin disorders including psoriasis anddermatitis; vascular disease; conditions involving abnormalproliferation of vascular epithelial cells; gastrointestinal ulcers;Menetrier's disease, secreting adenomas or protein loss syndrome; renaldisorders; angiogenic disorders; ocular disease such as age relatedmacular degeneration, presumed ocular histoplasmosis syndrome, retinalneovascularization from proliferative diabetic retinopathy, retinalvascularization, diabetic retinopathy, or age related maculardegeneration; bone associated pathologies such as osteoarthritis,rickets and osteoporosis; damage following a cerebral ischemic event;fibrotic or edemia diseases such as hepatic cirrhosis, lung fibrosis,carcoidosis, throiditis, hyperviscosity syndrome systemic, OslerWeber-Rendu disease, chronic occlusive pulmonary disease, or edemafollowing burns, trauma, radiation, stroke, hypoxia or ischemia;hypersensitivity reaction of the skin; diabetic retinopathy and diabeticnephropathy; Guillain-Barre syndrome; graft versus host disease ortransplant rejection; Paget's disease; bone or joint inflammation;photoaging (e.g. caused by UV radiation of human skin); benign prostatichypertrophy; certain microbial infections including microbial pathogensselected from adenovirus, hantaviruses, Borrelia burgdorferi, Yersiniaspp. and Bordetella pertussis; thrombus caused by platelet aggregation;reproductive conditions such as endometriosis, ovarian hyperstimulationsyndrome, preeclampsia, dysfunctional uterine bleeding, ormenometrorrhagia; synovitis; atheroma; acute and chronic nephropathies(including proliferative glomerulonephritis and diabetes-induced renaldisease); eczema; hypertrophic scar formation; endotoxic shock andfungal infection; familial adenomatosis polyposis; neurodedenerativediseases (e.g. Alzheimer's disease, AIDS-related dementia, Parkinson'sdisease, amyotrophic lateral sclerosis, retinitis pigmentosa, spinalmuscular atrophy and cerebellar degeneration); myelodysplasticsyndromes; aplastic anemia; ischemic injury; fibrosis of the lung,kidney or liver; T-cell mediated hypersensitivity disease; infantilehypertrophic pyloric stenosis; urinary obstructive syndrome; psoriaticarthritis; and Hasimoto's thyroiditis. Preferred non-malignantindications for therapy herein include psoriasis, endometriosis,scleroderma, vascular disease (e.g. restenosis, artherosclerosis,coronary artery disease, or hypertension), colon polyps, fibroadenoma orrespiratory disease (e.g. asthma, chronic bronchitis, bronchieactasis orcystic fibrosis).

Treatment with the HER2 antibody will result in an improvement in thesigns or symptoms of disease. For instance, where the disease beingtreated is cancer, such therapy may result in an improvement in survival(overall survival and/or progression free survival) and/or may result inan objective clinical response (partial or complete).

Preferably, the HER2 antibody in the composition administered is a nakedantibody. However, the HER2 antibody administered may be conjugated witha cytotoxic agent. Preferably, the immunoconjugate and/or HER2 proteinto which it is bound is/are internalized by the cell, resulting inincreased therapeutic efficacy of the immunoconjugate in killing thecancer cell to which it binds. In a preferred embodiment, the cytotoxicagent targets or interferes with nucleic acid in the cancer cell.Examples of such cytotoxic agents include maytansinoids, calicheamicins,ribonucleases and DNA endonucleases.

The HER2 antibody is administered to a human patient in accord withknown methods, such as intravenous administration, e.g., as a bolus orby continuous infusion over a period of time, by intramuscular,intraperitoneal, intracerobrospinal, subcutaneous, intra-articular,intrasynovial, intrathecal, oral, topical, or inhalation routes.Intravenous administration of antibody composition is preferred.

For the prevention or treatment of disease, the appropriate dosage ofHER2 antibody will depend on the type of disease to be treated, asdefined above, the severity and course of the disease, whether the HER2antibody is administered for preventive or therapeutic purposes,previous therapy, the patient's clinical history and response to theHER2 antibody, and the discretion of the attending physician. The HER2antibody is suitably administered to the patient at one time or over aseries of treatments. Depending on the type and severity of the disease,about 1 μg/kg to 50 mg/kg (e.g. 0.1-20 mg/kg) of HER2 antibody is aninitial candidate dosage for administration to the patient, whether, forexample, by one or more separate administrations, or by continuousinfusion. In one embodiment, the initial infusion time for the HER2antibody may be longer than subsequent infusion times, for instanceapproximately 90 minutes for the initial infusion, and approximately 30minutes for subsequent infusions (if the initial infusion is welltolerated). The preferred dosage of the HER2 antibody will be in therange from about 0.05 mg/kg to about 10 mg/kg. Thus, one or more dosesof about 0.5 mg/kg, 2.0 mg/kg, 4.0 mg/kg or 10 mg/kg (or any combinationthereof) may be administered to the patient. Such doses may beadministered intermittently, e.g. every week or every three weeks (e.g.such that the patient receives from about two to about twenty, e.g.about six doses of the HER2 antibody). An initial higher loading dose,followed by one or more lower doses may be administered. In oneembodiment, the HER2 antibody is administered as a loading dose ofapproximately 840 mg followed by approximately 420 mg administeredapproximately every 3 weeks. In another embodiment, the HER2 antibody isadministered as a loading dose of approximately 1050 mg followed byapproximately 525 mg administered approximately every 3 weeks.

Other therapeutic agents may be combined with the HER2 antibody. Suchcombined administration includes coadministration or concurrentadministration, using separate formulations or a single pharmaceuticalformulation, and consecutive administration in either order, whereinpreferably there is a time period while both (or all) active agentssimultaneously exert their biological activities. Thus, the othertherapeutic agent may be administered prior to, or following,administration of the HER2 antibody. In this embodiment, the timingbetween at least one administration of the other therapeutic agent andat least one administration of the HER2 antibody is preferablyapproximately 1 month or less, and most preferably approximately 2 weeksor less. Alternatively, the other therapeutic agent and the HER2antibody are administered concurrently to the patient, in a singleformulation or separate formulations.

Examples of other therapeutic agents that can be combined with the HER2antibody include any one or more of: a chemotherapeutic agent, such asan anti-metabolite, e.g. gemcitabine; a second, different HER2 antibody(for example, a growth inhibitory HER2 antibody such as Trastuzumab, ora HER2 antibody which induces apoptosis of a HER2-overexpressing cell,such as 7C2, 7F3 or humanized variants thereof); a second antibodydirected against another tumor associated antigen, such as EGFR, HER3,HER4; anti-hormonal compound, e.g., an anti-estrogen compound such astamoxifen, or an aromatase inhibitor; a cardioprotectant (to prevent orreduce any myocardial dysfunction associated with the therapy); acytokine; an EGFR-targeted drug (such as Erlitonib, Gefitinib, orCetuximab); an anti-angiogenic agent (especially Bevacizumab sold byGenentech under the trademark AVASTIN®); a tyrosine kinase inhibitor; aCOX inhibitor (for instance a COX-1 or COX-2 inhibitor); non-steroidalanti-inflammatory drug, Celecoxib (CELEBREX®); farnesyl transferaseinhibitor (for example, Tipifarnib/ZARNESTRA® R1115777 available fromJohnson and Johnson or Lonafarnib SCH66336 available fromSchering-Plough); antibody that binds oncofetal protein CA 125 such asOregovomab (MoAb B43.13); HER2 vaccine (such as HER2 AutoVac vaccinefrom Pharmexia, or APC8024 protein vaccine from Dendreon, or HER2peptide vaccine from GSK/Corixa); another HER targeting therapy (e.g.trastuzumab, cetuximab, gefitinib, erlotinib, C11033, GW2016 etc); Rafand/or ras inhibitor (see, for example, WO 2003/86467); Doxil;Topetecan; taxane; GW572016; TLK286; EMD-7200; a medicament that treatsnausea such as a serotonin antagonist, steroid, or benzodiazepine; amedicament that prevents or treats skin rash or standard acne therapies,including topical or oral antibiotic; a body temperature-reducingmedicament such as acetaminophen, diphenhydramine, or meperidine;hematopoietic growth factor, etc.

Suitable dosages for any of the above coadministered agents are thosepresently used and may be lowered due to the combined action (synergy)of the agent and HER2 antibody. Treatment with the combination of theHER2 antibody composition and other therapeutic agent may result in asynergistic, or greater than additive, therapeutic benefit to thepatient.

If a chemotherapeutic agent is administered, it is usually administeredat dosages known therefor, or optionally lowered due to combined actionof the drugs or negative side effects attributable to administration ofthe chemotherapeutic agent. Preparation and dosing schedules for suchchemotherapeutic agents may be used according to manufacturers'instructions or as determined empirically by the skilled practitioner.Preparation and dosing schedules for such chemotherapy are alsodescribed in Chemotherapy Service Ed., M. C. Perry, Williams & Wilkins,Baltimore, Md. (1992).

In addition to the above therapeutic regimes, the patient may besubjected to surgical removal of cancer cells and/or radiation therapy.

VII. Deposit of Materials

The following hybridoma cell lines have been deposited with the AmericanType Culture Collection, 10801 University Boulevard, Manassas, Va.20110-2209, USA (ATCC):

Antibody Designation ATCC No. Deposit Date 7C2 ATCC HB-12215 Oct. 17,1996 7F3 ATCC HB-12216 Oct. 17, 1996 4D5 ATCC CRL 10463 May 24, 1990 2C4ATCC HB-12697 Apr. 8, 1999

Further details of the invention are illustrated by the followingnon-limiting Example. The disclosures of all citations in thespecification are expressly incorporated herein by reference.

EXAMPLE 1

This example describes the characterization of a composition comprisinga main species HER2 antibody that binds to domain II of HER2(pertuzumab) and acidic variants thereof.

Pertuzumab is a recombinant humanized monoclonal antibody, generatedbased on human IgG1(κ) framework. It comprises two heavy chains (448residues) and two light chains (214 residues). The two heavy chains arelinked by two interchain disulfides and each light chain is attached toa heavy chain through one interchain disulfide. There is an N-linkedglycosylation site in the Fc region of pertuzumab at Asn-299 of the twoheavy chains. Pertuzumab differs from HERCEPTIN® (Trastuzumab) in theepitope binding regions of the light chain (12 amino acid differences)and the heavy chain (30 amino acid differences). As a result of thesedifferences, pertuzumab binds to a completely different epitope on theHER2 receptor. Binding of pertuzumab to the HER2 receptor on humanepithelial cells prevents it from forming complexes with other membersof the HER receptor family (Agus et al., Cancer Cell 2:127-137 (2002)).By blocking complex formation, pertuzumab prevents thegrowth-stimulatory effects of ligands for the complexes (e.g., EGF andheregulin). In vitro experiments demonstrated that both pertuzumab andpertuzumab-Fab inhibit the binding of heregulin (HRG) to MCF7 cells, andthat the HRG-stimulated phosphorylation of the HER2-HER3 complex can beinhibited by both pertuzumab and pertuzumab-Fab (Agus et al., CancerCell 2:127-137 (2002)). Furthermore, in vivo inhibition of tumor growthby pertuzumab and a polyethylene glycol derivatized Fab of pertuzumabwere found to be comparable in a murine prostate cancer xenograft model(Agus et al., Cancer Cell 2:127-137 (2002)). These data suggest that theFc region of the antibody is not necessary for the inhibition of tumorgrowth, and moreover, bivalency and Fc-mediated effector functions arenot required for in vivo or in vitro biological activity.

In this example, the main peak of pertuzumab was collected from a cationexchange column and incubated in cell culture media or processed usingstandard antibody purification operations. Acidic variants formed uponincubation of main peak with cell culture media components. Acidicvariants of monoclonal antibodies are modified forms of the desiredproduct that elute earlier than the main peak upon separation by cationexchange chromatography. Subtle differences in the amount and/ordistribution of acidic variants are often observed pre- and post-processchanges and pose a challenge to demonstrating product comparability.Purification operations had little effect on formation of acidicvariants. Variants identified in the acidic variant fraction includedglycated variant, deamidated variant, disulfide-reduced variant,sialylated variant, and non-reducible variant. Collectively, the acidicvariants were fully potent.

Amongst other things, the purpose of this study was to: betterunderstand the impact of cell culture and recovery processes onpertuzumab acidic variant formation, characterize the predominant acidicvariants of pertuzumab, and evaluate the impact of acidic variants onpharmacokinetics (PK).

Rat pharmacokinetic results show that the area under the curve for theacidic variant fraction and main peak fraction were equivalent topertuzumab starting material (geometric mean ratios 0.96 and 0.95,respectively). These results demonstrate that although acidic variantsare chemically different from the main peak they have equivalentpharmacokinetics.

Methods and Results

FIG. 10 depicts the experimental design for isolation of cation exchangeMP (Main Peak) and AV (Acidic Variants), cell culture, recovery, and PK(pharmacokinetics) evaluation and analytical testing. Freshmedia=standard media; spent media=standard media after 12 days of cellculture, cells were removed by centrifugation. Dissolved oxygen, pH, andother parameters were not controlled.

A. Isolation of Main Peak and Acidic Variants

Charge variants of pertuzumab were separated on a 4.0×250 mm DIONEXPROPAC WCX-10™ cation exchange (CEX) column using the followingconditions:

Buffer A: 20 mM BisTris, pH 6.0

Buffer B: 20 mM BisTris, 200 mM NaCl, pH 6.0

Gradient: 0.5% B/min delivered at 1.0 mL/min

Column Temperature: 35° C.

Detection: 280 nm

A typical chromatogram is shown in FIG. 11. AV (acidic variant) and MP(main peak) fractions were collected.

Potency and monomer content were similar among the pertuzmab startingmaterial, main peak, and acidic variants (FIG. 12). Purity of the mainpeak and acidic variant CEX fractions was acceptable forpharmacokinetics studies based on the criteria of 90% purity by CEX(FIG. 12).

B. Main Peak Spiking Experiments

Pertuzumab main peak isolated by CEX was spiked into either fresh orspent cell culture media (no cells) and incubated for 12 days at 37° C.as outlined in FIG. 10. Samples at various time points were directlyanalyzed by CEX or after isolation by protein A. Main peak was alsospiked into media+/−various media components such as glucose andpeptone. In addition, main peak was processed through standard recoveryoperations such as protein A chromatorgraphy (ProA), low pH treatment,and SP Sepharose Fast Flow (SPFF) for multiple cycles and analyzed byCEX.

CEX profiles of main peak incubated for 12 days in fresh or spent mediawere similar (FIGS. 13 and 14). Main peak decreased more afterincubation in fresh media than in spent media. Removal of various mediacomponents did affect the decrease of main peak. Percent main peak inincubated samples was the same with and without protein A isolation.Incubation in media buffer alone caused a loss of main peak.

Protein A isolation of main peak from media did not affect the CEXprofile demonstrating that modifications during incubation do not affectprotein A binding or elution. Recovery operations had little or noeffect on the percent CEX main peak.

C. Characterization of Acidic Variants

Pertuzumab acidic variants were isolated by CEX from pertuzumab startingmaterial or main peak incubated in cell culture media The isolatedacidic variants were analyzed by the methods listed in FIG. 15. Acidicvariants comprise 21% of total peak area, therefore about 80% (17% of21%) of acidic variants were identified. Deamidated forms could not bequantified.

Forms identified in acidic variants generated by main peak incubatedwith media were the same as those identified in pertuzumab startingmaterial. The following forms were detected: sialylated variant,disulfide reduced variant, glycated variant, non-reducible variant, anddeamidated variant. Higher order glycated forms were identified byelectrospray ionization-mass spectrometry (ESI-MS) after reduction andPNGase treatment.

D. Pharmacokinetics (PK) Study

A single intravenous (IV) dose of 10 mg/kg, 12 rats per arm, 3 arms(acidic variants, main peak, pertuzumab starting material). Extensive PKsampling was conducted for 35 days. Geometric Mean Ratio of AUC (Day0-14) between acidic, main peak, and pertuzumab starting material.Geometric Mean Ratio=GM Sample/GM IgG1 Starting Material. Pertuzumabconcentration versus time curve were similar for the pertuzumab startingmaterial, acidic variant, and main peak (FIGS. 16 and 17). Nosignificant difference in exposure was observed between acidic variants,main peak, and pertuzumab starting material. The GMR was ˜1.0 with 90%CI between 0.80-1.25.

CONCLUSIONS

Multiple cell culture factors contribute to acidic variant formation,but recovery was not shown to effect acidic variant formation. Disulfidereduced, non-reducible, sialylated, glycated, and deamidated variantswere identified in the acidic fraction. Acidic fraction isolated frompertuzumab starting material and those generated by incubation of CEXmain peak contained the same forms. Acidic variants, main peak, andpertuzumab starting material had the same pharmacokinetics.

What is claimed is:
 1. A composition comprising a main species HER2antibody that binds to domain II of HER2 and comprises variable lightand variable heavy amino acid sequences in SEQ ID Nos. 3 and 4,respectively, and acidic variants thereof comprising disulfide reducedvariant and non-reducible variant of the main species antibody.
 2. Thecomposition of claim 1 wherein the composition further comprisesglycated variant of the main species antibody.
 3. The composition ofclaim 1 further comprising glycated variant of the main speciesantibody, deamidated variant of the main species antibody, andsialylated variant of the main species antibody.
 4. The composition ofclaim 1 comprising less than about 25% acidic variants.
 5. Thecomposition of claim 1 wherein the main species HER2 antibody and theacidic variant are both intact antibodies.
 6. The composition of claim 1wherein the main species HER2 antibody comprises light chain and heavychain amino acid sequences in SEQ ID Nos. 15 and 16, respectively. 7.The composition of claim 1 further comprising an amino-terminal leaderextension variant of the main species antibody.
 8. The composition ofclaim 7 wherein the amino-terminal leader extension comprises VHS-. 9.The composition of claim 8 wherein the amino-terminal leader extensionconsists of VHS-.
 10. The composition of claim 1 further comprising anamino acid sequence variant of the main species HER2 antibody selectedfrom the group consisting of an antibody comprising a C-terminal lysineresidue on one or both heavy chains thereof, and an antibody with one ormore oxidized methionine residues.
 11. A pharmaceutical formulationcomprising the composition of claim 1 in a pharmaceutically acceptablecarrier.
 12. The pharmaceutical formulation of claim 11 which issterile.
 13. A composition comprising a main species HER2 antibodycomprising variable light and variable heavy sequences of SEQ ID Nos. 3and 4, respectively, and acidic variants of the main species antibody,wherein the acidic variants comprise glycated variant, deamidatedvariant, disulfide reduced variant, sialylated variant, andnon-reducible variant, wherein the acidic variants comprise less than25% of the composition, and wherein the acidic variants have essentiallythe same pharmacokinetics as the main species antibody.
 14. Apharmaceutical formulation comprising the composition of claim 13 in apharmaceutically acceptable carrier.
 15. A composition comprising a mainspecies HER2 antibody that binds to domain II of HER2 and comprisesvariable light and variable heavy amino acid sequences in SEQ ID Nos. 3and 4, respectively, and acidic variant thereof comprising non-reduciblevariant of the main species antibody.
 16. A pharmaceutical compositioncomprising: (a) a main species HER2 antibody comprising variable lightand variable heavy sequences of SEQ ID Nos. 3 and 4, respectively; (b)acidic variants of the main species antibody, wherein the acidicvariants comprise glycated variant, deamidated variant, disulfidereduced variant, sialylated variant, and non-reducible variant, whereinthe acidic variants comprise less than 25% of the composition, andwherein the acidic variants have essentially the same pharmacokineticsas the main species antibody; and (c) a pharmaceutically acceptablecarrier.